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

pkg/dev_compiler/lib/src/compiler/code_generator.dart

Index: pkg/dev_compiler/lib/src/compiler/code_generator.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/code_generator.dart b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
index a642fe4da82618211f0ff3717842618acf9f03c7..7968477d5d816011b86da3a396f3464ee81f64e7 100644
--- a/pkg/dev_compiler/lib/src/compiler/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
@@ -754,8 +754,8 @@ class CodeGenerator extends GeneralizingAstVisitor
     _defineClass(classElem, className, classExpr, isCallable, body);
 
     // Emit things that come after the ES6 `class ... { ... }`.
-    var jsPeerName = _getJSPeerName(classElem);
-    _setBaseClass(classElem, className, jsPeerName, body);
+    var jsPeerNames = _getJSPeerNames(classElem);
+    _setBaseClass(classElem, className, jsPeerNames, body);
 
     _emitClassTypeTests(classElem, className, body);
 
@@ -774,7 +774,9 @@ class CodeGenerator extends GeneralizingAstVisitor
 
     body = <JS.Statement>[classDef];
     _emitStaticFields(staticFields, staticFieldOverrides, classElem, body);
-    _registerExtensionType(classElem, jsPeerName, body);
+    for (var peer in jsPeerNames) {
+      _registerExtensionType(classElem, peer, body);
+    }
     return _statement(body);
   }
 
@@ -1569,16 +1571,19 @@ class CodeGenerator extends GeneralizingAstVisitor
   ///
   /// For example for dart:_interceptors `JSArray` this will return "Array",
   /// referring to the JavaScript built-in `Array` type.
-  String _getJSPeerName(ClassElement classElem) {
-    var jsPeerName = getAnnotationName(
+  List<String> _getJSPeerNames(ClassElement classElem) {
+    var jsPeerNames = getAnnotationName(
         classElem,
         (a) =>
             isJsPeerInterface(a) ||
             isNativeAnnotation(a) && _extensionTypes.isNativeClass(classElem));
-    if (jsPeerName != null && jsPeerName.contains(',')) {
-      jsPeerName = jsPeerName.split(',')[0];
+    if (jsPeerNames != null) {
+      // Omit the special name "!nonleaf" and any future hacks starting with "!"
+      return jsPeerNames.split(',').where(
+          (peer) => !peer.startsWith("!")).toList();
+    } else {
+      return [];
     }
-    return jsPeerName;
   }
 
   void _registerExtensionType(
@@ -1590,12 +1595,14 @@ class CodeGenerator extends GeneralizingAstVisitor
   }
 
   void _setBaseClass(ClassElement classElem, JS.Expression className,
-      String jsPeerName, List<JS.Statement> body) {
-    if (jsPeerName != null && classElem.typeParameters.isNotEmpty) {
-      // TODO(jmesserly): we should really just extend Array in the first place.
-      var newBaseClass = js.call('dart.global.#', [jsPeerName]);
-      body.add(js.statement(
-          'dart.setExtensionBaseClass(#, #);', [className, newBaseClass]));
+      List<String> jsPeerNames, List<JS.Statement> body) {
+    if (jsPeerNames.isNotEmpty && classElem.typeParameters.isNotEmpty) {
+      for (var peer in jsPeerNames) {
+        // TODO(jmesserly): we should just extend Array in the first place
+        var newBaseClass = js.call('dart.global.#', [peer]);
+        body.add(js.statement(
+            'dart.setExtensionBaseClass(#, #);', [className, newBaseClass]));

[vsm, 2016/10/17 23:08:29]

Hmm - I'm a little surprised this works.  Looking at the code for
setExtensionBaseClass, it looks like a second call will undo the first.

Have you tried internal apps under Chrome to make sure they still work?  Our
test coverage is probably lacking here.

[vsm, 2016/10/17 23:17:59]

Ahh, looks like combination of type parameters and multiple peers never comes
up.  :-)  I see no new calls in the generated code from this.

Do we expect only one peer to exist (i.e., not be undefined)?  If so, maybe we
just need a check in setExtensionBaseClass?  If more - is the code supposed to
prefer one?

+      }
     } else if (_hasDeferredSupertype.contains(classElem)) {
       var newBaseClass = _emitType(classElem.type.superclass,
           nameType: false, subClass: classElem, className: className);