diff --git a/core/block.js b/core/block.js
index 2f816215428..a165476d062 100644
--- a/core/block.js
+++ b/core/block.js
@@ -15,8 +15,6 @@
  */
 goog.module('Blockly.Block');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const Extensions = goog.require('Blockly.Extensions');
 const Tooltip = goog.require('Blockly.Tooltip');
 const arrayUtils = goog.require('Blockly.utils.array');
@@ -27,6 +25,8 @@ const fieldRegistry = goog.require('Blockly.fieldRegistry');
 const idGenerator = goog.require('Blockly.utils.idGenerator');
 const object = goog.require('Blockly.utils.object');
 const parsing = goog.require('Blockly.utils.parsing');
+/* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
 const {Align, Input} = goog.require('Blockly.Input');
 const {ASTNode} = goog.require('Blockly.ASTNode');
 const {Blocks} = goog.require('Blockly.blocks');
diff --git a/core/bump_objects.js b/core/bump_objects.js
index 2b7dc82a7f4..3cff5ed51b8 100644
--- a/core/bump_objects.js
+++ b/core/bump_objects.js
@@ -15,11 +15,11 @@
  */
 goog.module('Blockly.bumpObjects');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const eventUtils = goog.require('Blockly.Events.utils');
 const mathUtils = goog.require('Blockly.utils.math');
 /* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
+/* eslint-disable-next-line no-unused-vars */
 const {BlockSvg} = goog.requireType('Blockly.BlockSvg');
 /* eslint-disable-next-line no-unused-vars */
 const {IBoundedElement} = goog.requireType('Blockly.IBoundedElement');
diff --git a/core/events/events.js b/core/events/events.js
index d4cb5f7d49d..e6e1ef5b493 100644
--- a/core/events/events.js
+++ b/core/events/events.js
@@ -15,9 +15,9 @@
  */
 goog.module('Blockly.Events');
 
-const Abstract = goog.require('Blockly.Events.Abstract');
 const deprecation = goog.require('Blockly.utils.deprecation');
 const eventUtils = goog.require('Blockly.Events.utils');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 const {BlockBase} = goog.require('Blockly.Events.BlockBase');
 const {BlockChange} = goog.require('Blockly.Events.BlockChange');
 const {BlockCreate} = goog.require('Blockly.Events.BlockCreate');
diff --git a/core/events/events_abstract.js b/core/events/events_abstract.js
index c20d894db6b..627c1fe9861 100644
--- a/core/events/events_abstract.js
+++ b/core/events/events_abstract.js
@@ -118,4 +118,4 @@ Abstract.prototype.getEventWorkspace_ = function() {
   return workspace;
 };
 
-exports = Abstract;
+exports.Abstract = Abstract;
diff --git a/core/events/events_block_base.js b/core/events/events_block_base.js
index c243575fa29..3a0842def95 100644
--- a/core/events/events_block_base.js
+++ b/core/events/events_block_base.js
@@ -15,8 +15,8 @@
  */
 goog.module('Blockly.Events.BlockBase');
 
-const Abstract = goog.require('Blockly.Events.Abstract');
 const object = goog.require('Blockly.utils.object');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const {Block} = goog.requireType('Blockly.Block');
 
diff --git a/core/events/events_comment_base.js b/core/events/events_comment_base.js
index 63de88dfe84..a54e8e0e87d 100644
--- a/core/events/events_comment_base.js
+++ b/core/events/events_comment_base.js
@@ -15,11 +15,11 @@
  */
 goog.module('Blockly.Events.CommentBase');
 
-const AbstractEvents = goog.require('Blockly.Events.Abstract');
 const Xml = goog.require('Blockly.Xml');
 const eventUtils = goog.require('Blockly.Events.utils');
 const object = goog.require('Blockly.utils.object');
 const utilsXml = goog.require('Blockly.utils.xml');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const {CommentCreate} = goog.requireType('Blockly.Events.CommentCreate');
 /* eslint-disable-next-line no-unused-vars */
@@ -32,7 +32,7 @@ const {WorkspaceComment} = goog.requireType('Blockly.WorkspaceComment');
  * Abstract class for a comment event.
  * @param {!WorkspaceComment=} opt_comment The comment this event
  *     corresponds to.  Undefined for a blank event.
- * @extends {AbstractEvents}
+ * @extends {Abstract}
  * @constructor
  * @alias Blockly.Events.CommentBase
  */
@@ -69,7 +69,7 @@ const CommentBase = function(opt_comment) {
    */
   this.recordUndo = eventUtils.getRecordUndo();
 };
-object.inherits(CommentBase, AbstractEvents);
+object.inherits(CommentBase, Abstract);
 
 /**
  * Encode the event as JSON.
diff --git a/core/events/events_ui_base.js b/core/events/events_ui_base.js
index cd7ad1d2e20..8f963f1757b 100644
--- a/core/events/events_ui_base.js
+++ b/core/events/events_ui_base.js
@@ -17,8 +17,8 @@
  */
 goog.module('Blockly.Events.UiBase');
 
-const Abstract = goog.require('Blockly.Events.Abstract');
 const object = goog.require('Blockly.utils.object');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 
 
 /**
diff --git a/core/events/events_var_base.js b/core/events/events_var_base.js
index fd919a061bb..2f72cd9828d 100644
--- a/core/events/events_var_base.js
+++ b/core/events/events_var_base.js
@@ -15,8 +15,8 @@
  */
 goog.module('Blockly.Events.VarBase');
 
-const Abstract = goog.require('Blockly.Events.Abstract');
 const object = goog.require('Blockly.utils.object');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const {VariableModel} = goog.requireType('Blockly.VariableModel');
 
diff --git a/core/events/utils.js b/core/events/utils.js
index c405490b7bd..9f1c5c229e0 100644
--- a/core/events/utils.js
+++ b/core/events/utils.js
@@ -17,11 +17,11 @@
  */
 goog.module('Blockly.Events.utils');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const idGenerator = goog.require('Blockly.utils.idGenerator');
 const registry = goog.require('Blockly.registry');
 /* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
+/* eslint-disable-next-line no-unused-vars */
 const {BlockCreate} = goog.requireType('Blockly.Events.BlockCreate');
 /* eslint-disable-next-line no-unused-vars */
 const {BlockMove} = goog.requireType('Blockly.Events.BlockMove');
diff --git a/core/events/workspace_events.js b/core/events/workspace_events.js
index 726a114c079..d240f3d93e9 100644
--- a/core/events/workspace_events.js
+++ b/core/events/workspace_events.js
@@ -15,10 +15,10 @@
  */
 goog.module('Blockly.Events.FinishedLoading');
 
-const Abstract = goog.require('Blockly.Events.Abstract');
 const eventUtils = goog.require('Blockly.Events.utils');
 const object = goog.require('Blockly.utils.object');
 const registry = goog.require('Blockly.registry');
+const {Abstract} = goog.require('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const {Workspace} = goog.requireType('Blockly.Workspace');
 
diff --git a/core/mutator.js b/core/mutator.js
index 97adf1b43df..34e42b71fda 100644
--- a/core/mutator.js
+++ b/core/mutator.js
@@ -17,13 +17,13 @@
  */
 goog.module('Blockly.Mutator');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const dom = goog.require('Blockly.utils.dom');
 const eventUtils = goog.require('Blockly.Events.utils');
 const internalConstants = goog.require('Blockly.internalConstants');
 const toolbox = goog.require('Blockly.utils.toolbox');
 const xml = goog.require('Blockly.utils.xml');
+/* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
 const {BlockChange} = goog.require('Blockly.Events.BlockChange');
 /* eslint-disable-next-line no-unused-vars */
 const {BlockSvg} = goog.requireType('Blockly.BlockSvg');
diff --git a/core/procedures.js b/core/procedures.js
index a6c819f5995..ab6b9125c39 100644
--- a/core/procedures.js
+++ b/core/procedures.js
@@ -15,12 +15,12 @@
  */
 goog.module('Blockly.Procedures');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const Variables = goog.require('Blockly.Variables');
 const Xml = goog.require('Blockly.Xml');
 const eventUtils = goog.require('Blockly.Events.utils');
 const utilsXml = goog.require('Blockly.utils.xml');
+/* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
 const {Blocks} = goog.require('Blockly.blocks');
 /* eslint-disable-next-line no-unused-vars */
 const {Block} = goog.requireType('Blockly.Block');
diff --git a/core/registry.js b/core/registry.js
index b2420f86aa9..4b80d2560d5 100644
--- a/core/registry.js
+++ b/core/registry.js
@@ -18,7 +18,7 @@
 goog.module('Blockly.registry');
 
 /* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const {Cursor} = goog.requireType('Blockly.Cursor');
 /* eslint-disable-next-line no-unused-vars */
diff --git a/core/trashcan.js b/core/trashcan.js
index 3b7dbafc86f..e9a8a48196e 100644
--- a/core/trashcan.js
+++ b/core/trashcan.js
@@ -15,8 +15,6 @@
  */
 goog.module('Blockly.Trashcan');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 /* eslint-disable-next-line no-unused-vars */
 const blocks = goog.requireType('Blockly.serialization.blocks');
 const browserEvents = goog.require('Blockly.browserEvents');
@@ -27,6 +25,8 @@ const registry = goog.require('Blockly.registry');
 const toolbox = goog.require('Blockly.utils.toolbox');
 const uiPosition = goog.require('Blockly.uiPosition');
 /* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
+/* eslint-disable-next-line no-unused-vars */
 const {BlocklyOptions} = goog.requireType('Blockly.BlocklyOptions');
 const {ComponentManager} = goog.require('Blockly.ComponentManager');
 const {DeleteArea} = goog.require('Blockly.DeleteArea');
diff --git a/core/workspace.js b/core/workspace.js
index 3a4af4359dc..51995a75784 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -15,8 +15,6 @@
  */
 goog.module('Blockly.Workspace');
 
-/* eslint-disable-next-line no-unused-vars */
-const Abstract = goog.requireType('Blockly.Events.Abstract');
 const arrayUtils = goog.require('Blockly.utils.array');
 const eventUtils = goog.require('Blockly.Events.utils');
 const idGenerator = goog.require('Blockly.utils.idGenerator');
@@ -25,6 +23,8 @@ const registry = goog.require('Blockly.registry');
 /* eslint-disable-next-line no-unused-vars */
 const toolbox = goog.requireType('Blockly.utils.toolbox');
 /* eslint-disable-next-line no-unused-vars */
+const {Abstract} = goog.requireType('Blockly.Events.Abstract');
+/* eslint-disable-next-line no-unused-vars */
 const {BlocklyOptions} = goog.requireType('Blockly.BlocklyOptions');
 /* eslint-disable-next-line no-unused-vars */
 const {Block} = goog.requireType('Blockly.Block');
diff --git a/scripts/gulpfiles/chunks.json b/scripts/gulpfiles/chunks.json
index 4f9b9449267..c034a0d896a 100644
--- a/scripts/gulpfiles/chunks.json
+++ b/scripts/gulpfiles/chunks.json
@@ -26,18 +26,6 @@
     "./core/field_checkbox.js",
     "./core/field_angle.js",
     "./core/toolbox/collapsible_category.js",
-    "./core/renderers/zelos/measurables/top_row.js",
-    "./core/renderers/zelos/measurables/inputs.js",
-    "./core/renderers/zelos/measurables/row_elements.js",
-    "./core/renderers/zelos/marker_svg.js",
-    "./core/renderers/zelos/renderer.js",
-    "./core/field_textinput.js",
-    "./core/field_image.js",
-    "./core/renderers/zelos/info.js",
-    "./core/renderers/zelos/path_object.js",
-    "./core/renderers/zelos/drawer.js",
-    "./core/renderers/zelos/constants.js",
-    "./core/renderers/zelos/measurables/bottom_row.js",
     "./core/renderers/zelos/zelos.js",
     "./core/renderers/thrasos/renderer.js",
     "./core/renderers/thrasos/info.js",
@@ -76,18 +64,23 @@
     "./core/utils/useragent.js",
     "./core/utils/svg.js",
     "./core/utils/dom.js",
+    "./core/utils/idgenerator.js",
     "./core/connection_checker.js",
-    "./core/keyboard_nav/ast_node.js",
-    "./core/keyboard_nav/cursor.js",
-    "./core/registry.js",
+    "./core/toolbox/separator.js",
+    "./core/toolbox/toolbox_item.js",
+    "./core/interfaces/i_selectable_toolbox_item.js",
+    "./core/interfaces/i_collapsible_toolbox_item.js",
+    "./core/toolbox/category.js",
+    "./core/serialization/exceptions.js",
+    "./core/interfaces/i_serializer.js",
+    "./core/serialization/registry.js",
+    "./core/serialization/priorities.js",
+    "./core/serialization/blocks.js",
+    "./core/utils/toolbox.js",
     "./core/utils/math.js",
-    "./core/utils/idgenerator.js",
     "./core/utils/array.js",
     "./core/workspace.js",
-    "./core/utils/object.js",
     "./core/events/events_block_delete.js",
-    "./core/toolbox/separator.js",
-    "./core/toolbox/toolbox_item.js",
     "./core/keyboard_nav/basic_cursor.js",
     "./core/keyboard_nav/tab_navigate_cursor.js",
     "./core/warning.js",
@@ -128,11 +121,25 @@
     "./core/options.js",
     "./core/interfaces/i_bounded_element.js",
     "./core/grid.js",
+    "./core/css.js",
     "./core/flyout_button.js",
     "./core/contextmenu_registry.js",
     "./core/theme/classic.js",
     "./core/blockly_options.js",
     "./core/utils.js",
+    "./core/renderers/zelos/measurables/top_row.js",
+    "./core/renderers/zelos/measurables/row_elements.js",
+    "./core/renderers/zelos/marker_svg.js",
+    "./core/renderers/zelos/measurables/inputs.js",
+    "./core/renderers/zelos/path_object.js",
+    "./core/renderers/zelos/drawer.js",
+    "./core/renderers/zelos/renderer.js",
+    "./core/utils/aria.js",
+    "./core/field_textinput.js",
+    "./core/field_image.js",
+    "./core/renderers/zelos/constants.js",
+    "./core/renderers/zelos/measurables/bottom_row.js",
+    "./core/renderers/zelos/info.js",
     "./core/renderers/measurables/top_row.js",
     "./core/renderers/measurables/statement_input.js",
     "./core/renderers/measurables/square_corner.js",
@@ -155,8 +162,11 @@
     "./core/renderers/measurables/input_row.js",
     "./core/renderers/measurables/inline_input.js",
     "./core/scrollbar.js",
+    "./core/interfaces/i_toolbox_item.js",
+    "./core/interfaces/i_toolbox.js",
     "./core/utils/metrics.js",
     "./core/interfaces/i_metrics_manager.js",
+    "./core/interfaces/i_flyout.js",
     "./core/metrics_manager.js",
     "./core/interfaces/i_deletable.js",
     "./core/interfaces/i_draggable.js",
@@ -186,14 +196,15 @@
     "./core/events/events_var_delete.js",
     "./core/variable_map.js",
     "./core/names.js",
-    "./core/events/events_block_base.js",
-    "./core/events/events_block_change.js",
     "./core/events/events_ui_base.js",
     "./core/events/events_marker_move.js",
     "./core/renderers/common/marker_svg.js",
     "./core/keyboard_nav/marker.js",
+    "./core/keyboard_nav/ast_node.js",
+    "./core/keyboard_nav/cursor.js",
     "./core/marker_manager.js",
     "./core/field_label.js",
+    "./core/input_types.js",
     "./core/interfaces/i_registrable_field.js",
     "./core/field_registry.js",
     "./core/input.js",
@@ -216,8 +227,10 @@
     "./core/procedures.js",
     "./core/workspace_svg.js",
     "./core/utils/rect.js",
+    "./core/utils/size.js",
     "./core/utils/coordinate.js",
     "./core/utils/style.js",
+    "./core/utils/deprecation.js",
     "./core/utils/svg_math.js",
     "./core/bubble_dragger.js",
     "./core/block_animations.js",
@@ -226,23 +239,9 @@
     "./core/browser_events.js",
     "./core/tooltip.js",
     "./core/block_svg.js",
-    "./core/interfaces/i_flyout.js",
-    "./core/interfaces/i_toolbox.js",
-    "./core/interfaces/i_toolbox_item.js",
-    "./core/interfaces/i_selectable_toolbox_item.js",
-    "./core/interfaces/i_collapsible_toolbox_item.js",
-    "./core/utils/aria.js",
-    "./core/utils/deprecation.js",
-    "./core/css.js",
-    "./core/toolbox/category.js",
-    "./core/input_types.js",
-    "./core/utils/size.js",
-    "./core/serialization/exceptions.js",
-    "./core/interfaces/i_serializer.js",
-    "./core/serialization/registry.js",
-    "./core/serialization/priorities.js",
-    "./core/serialization/blocks.js",
-    "./core/utils/toolbox.js",
+    "./core/events/events_block_base.js",
+    "./core/events/events_block_change.js",
+    "./core/utils/xml.js",
     "./core/connection_type.js",
     "./core/internal_constants.js",
     "./core/mutator.js",
@@ -252,13 +251,14 @@
     "./core/extensions.js",
     "./core/block.js",
     "./core/utils/string.js",
+    "./core/utils/object.js",
     "./core/dialog.js",
-    "./core/utils/xml.js",
     "./core/events/events_var_base.js",
     "./core/events/events_var_create.js",
     "./core/variable_model.js",
     "./core/variables.js",
     "./core/events/events_abstract.js",
+    "./core/registry.js",
     "./core/events/utils.js",
     "./core/xml.js",
     "./core/connection.js",