Use dart:html prefixes (e.g. webkitAudioNode) on other browsers

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
index d6f3423b7d6980e77c0caddf61502d10298f2b58..f6b12eb4e177eac173181c6cf0b940a1c307368c 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
@@ -501,10 +501,13 @@ setBaseClass(derived, base) {
 
 /// Like [setBaseClass] but for generic extension types, e.g. `JSArray<E>`
 setExtensionBaseClass(derived, base) {
-  // Mark the generic type as an extension type.
-  JS('', '#.prototype[#] = #', derived, _extensionType, derived);
-  // Link the prototype objects
-  JS('', '#.prototype.__proto__ = #.prototype', derived, base);
+  // Mark the generic type as an extension type and link the prototype objects
+  return JS('', '''(() => {
+    if ($base) {
+      $derived.prototype[$_extensionType] = $derived;
+      $derived.prototype.__proto__ = $base.prototype
+    }
+})()''');
 }
 
 /// Given a special constructor function that creates a function instances,