Add special case templates to handle Global/WindowEventHandlers

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 8f4d3632dd3caec50e9ac931c656134c9a892651..bf95296b0f4c6423847462e633ba13907bd9fad1 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -13546,7 +13546,7 @@ class Geoposition extends Interceptor native "Geoposition" {
 @DocsEditable()
 @DomName('GlobalEventHandlers')
 @Experimental() // untriaged
-abstract class GlobalEventHandlers extends Interceptor {
+abstract class GlobalEventHandlers extends EventTarget {
   // To suppress missing implicit constructor warnings.
   factory GlobalEventHandlers._() { throw new UnsupportedError("Not supported"); }
 
@@ -29166,7 +29166,7 @@ abstract class WindowBase64 extends Interceptor {
 @DocsEditable()
 @DomName('WindowEventHandlers')
 @Experimental() // untriaged
-abstract class WindowEventHandlers extends Interceptor {
+abstract class WindowEventHandlers extends EventTarget {
   // To suppress missing implicit constructor warnings.
   factory WindowEventHandlers._() { throw new UnsupportedError("Not supported"); }