Define __CE_registry as using the polyfilled CustomElementRegistry type, not the built-in type.

Author: bicknellr

packages/custom-elements/ts_src/CustomElementInternals.ts

@@ -413,9 +413,7 @@ export default class CustomElementInternals {
       return;
     }
 
-    return ((registry as unknown) as CustomElementRegistry).internal_localNameToDefinition(
-      localName
-    );
+    return registry.internal_localNameToDefinition(localName);
   }
 
   /**

packages/custom-elements/ts_src/Patch/HTMLElement.ts

@@ -11,7 +11,6 @@
 
 import AlreadyConstructedMarker from '../AlreadyConstructedMarker.js';
 import CustomElementInternals from '../CustomElementInternals.js';
-import CustomElementRegistry from '../CustomElementRegistry.js';
 import CEState from '../CustomElementState.js';
 import * as Native from './Native.js';
 
@@ -25,9 +24,7 @@ export default function (internals: CustomElementInternals) {
 
     // Always look up the definition from the global registry.
     const registry = document.__CE_registry!;
-    const definition = ((registry as unknown) as CustomElementRegistry).internal_constructorToDefinition(
-      constructor
-    );
+    const definition = registry.internal_constructorToDefinition(constructor);
     if (!definition) {
       throw new Error(
         'Failed to construct a custom element: ' +

packages/custom-elements/ts_src/custom-elements.ts

@@ -43,7 +43,7 @@ function installPolyfill() {
   const customElements = new CustomElementRegistry(internals);
 
   // The main document is associated with the global registry.
-  (document.__CE_registry as unknown) = customElements;
+  document.__CE_registry = customElements;
 
   Object.defineProperty(window, 'customElements', {
     configurable: true,

packages/custom-elements/ts_src/env.d.ts

@@ -9,9 +9,7 @@
  * rights grant found at http://polymer.github.io/PATENTS.txt
  */
 
-// When building externally, this file is always assumed to be a module, but by
-// default it isn't when building internally, so we need this export statement.
-export {};
+import CustomElementRegistry from './CustomElementRegistry.js';
 
 declare global {
   interface AlreadyConstructedMarkerType {