Name-based approach to cross frame support.

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 4a8670bd65178dbd7914982df4ac822520dfaddc..9f4449d9553869aa66619d446048d105f9597664 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
@@ -391,7 +391,28 @@ bool hasField(type, name) => _hasSigEntry(type, _fieldSig, name);
 
 final _extensionType = JS('', 'Symbol("extensionType")');
 
-getExtensionType(obj) => JS('', '#[#]', obj, _extensionType);
+getExtensionType(obj) {
+  var result = JS('', '#[#]', obj, _extensionType);
+  if (result != null) return result;
+
+  if (JS('bool', 'typeof # != "object" || # instanceof #.Object', obj, obj,
+      global_)) {
+    return null;
+  }
+
+  // This is an object from another frame.  Check to see if we have registered
+  // an extension in case this is a DOM/native type.
+  var jsType = JS('', '#.constructor', obj);
+  var tag = JS('', '#.name', jsType);
+  if (JS('bool', '#.has(#)', _extMap, tag)) {
+    var jsProto = JS('', '#.__proto__', obj);
+    var dartType = JS('', '#.get(#)', _extMap, tag);
+    _installExtension(jsType, jsProto, dartType);
+    return dartType;
+  }
+
+  return null;
+}
 
 final dartx = JS('', 'dartx');
 
@@ -437,6 +458,15 @@ void _installPropertiesForObject(jsProto) {
   }
 }
 
+var _extMap;
+
+_cacheExtension(jsProto, dartType) {
+  if (_extMap == null) _extMap = JS('', 'new Map()');
+  // TODO(vsm): Make this work on non-Chrome browsers.
+  var tag = JS('', '#.constructor.name', jsProto);
+  JS('', '#.set(#, #)', _extMap, tag, dartType);
+}
+
 /// Copy symbols from the prototype of the source to destination.
 /// These are the only properties safe to copy onto an existing public
 /// JavaScript class.
@@ -452,13 +482,21 @@ registerExtension(jsType, dartExtType) => JS(
   // broken.
   if (!jsProto) return;
 
-  $_installProperties(jsProto, $dartExtType, jsProto[$_extensionType]);
+  $_cacheExtension(jsProto, $dartExtType);
 
   // Mark the JS type's instances so we can easily check for extensions.
-  jsProto[$_extensionType] = $dartExtType;
+  $_installExtension(jsType, jsProto, dartExtType);
+})()''');
+
+_installExtension(jsType, jsProto, dartType) => JS(
+    '',
+    '''(() => {
+  $_installProperties(jsProto, $dartType, jsProto[$_extensionType]);
 
+  // Mark the JS type's instances so we can easily check for extensions.
+  jsProto[$_extensionType] = $dartType;
   function updateSig(sigF) {
-    let originalDesc = $getOwnPropertyDescriptor($dartExtType, sigF);
+    let originalDesc = $getOwnPropertyDescriptor($dartType, sigF);
     if (originalDesc === void 0) return;
     let originalSigFn = originalDesc.get;
     $assert_(originalSigFn);
@@ -468,7 +506,7 @@ registerExtension(jsType, dartExtType) => JS(
   updateSig($_fieldSig);
   updateSig($_getterSig);
   updateSig($_setterSig);
-})()''');
+ })()''');
 
 ///
 /// Mark a concrete type as implementing extension methods.