fix(labs): removing hasConstructed and setting privateIsConstructed t…

…o handle setting tabIndex

labs/behaviors/focusable.ts

@@ -30,7 +30,6 @@ const privateIsFocusable = Symbol('privateIsFocusable');
 const externalTabIndex = Symbol('externalTabIndex');
 const isUpdatingTabIndex = Symbol('isUpdatingTabIndex');
 const updateTabIndex = Symbol('updateTabIndex');
-const hasConstructed = Symbol('hasConstructed');
 
 /**
  * Mixes in focusable functionality for a class.
@@ -68,20 +67,18 @@ export function mixinFocusable<T extends MixinBase<LitElement>>(
       this[updateTabIndex]();
     }
 
-    [privateIsFocusable] = false;
+    [privateIsFocusable] = true;
     [externalTabIndex]: number | null = null;
     [isUpdatingTabIndex] = false;
-    [hasConstructed] = false;
 
     // tslint:disable-next-line:no-any
     constructor(...args: any[]) {
       super(...args);
       this[isFocusable] = true;
     }
 
-    connectedCallback() {
+    override connectedCallback() {
       super.connectedCallback();
-      this[hasConstructed] = true;
       this[updateTabIndex]();
     }
 
@@ -112,11 +109,6 @@ export function mixinFocusable<T extends MixinBase<LitElement>>(
     }
 
     [updateTabIndex]() {
-      if (!this[hasConstructed]) {
-        // Custom elements may not hydrate attributes during construction.
-        return;
-      }
-
       const internalTabIndex = this[isFocusable] ? 0 : -1;
       const computedTabIndex = this[externalTabIndex] ?? internalTabIndex;