Strictify DraftEditorLeaf.react.js

Summary:
happyflow

Didn't need to change any functionality too.

Reviewed By: gkz

Differential Revision: D19894146

fbshipit-source-id: 9d94eab312b979257aeb79a57e10c8590a42a63a

src/component/contents/DraftEditorLeaf.react.js

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @format
- * @flow
+ * @flow strict-local
  * @emails oncall+draft_js
  */
 
@@ -23,15 +23,25 @@ const isHTMLBRElement = require('isHTMLBRElement');
 const setDraftEditorSelection = require('setDraftEditorSelection')
   .setDraftEditorSelection;
 
+type CSSStyleObject = {
+  [property: string]: string | number,
+};
+
+type CustomStyleMap = {[name: string]: CSSStyleObject};
+type CustomStyleFn = (
+  style: DraftInlineStyle,
+  block: BlockNodeRecord,
+) => ?CSSStyleObject;
+
 type Props = {
   // The block that contains this leaf.
   block: BlockNodeRecord,
 
   // Mapping of style names to CSS declarations.
-  customStyleMap: Object,
+  customStyleMap: CustomStyleMap,
 
   // Function that maps style names to CSS style objects.
-  customStyleFn: Function,
+  customStyleFn: CustomStyleFn,
 
   // Whether to force the DOM selection after render.
   forceSelection: boolean,