Fix runtimeType.toString for tear-offs.

sdk/lib/_internal/compiler/js_lib/js_helper.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library _js_helper;
 
 import 'dart:_async_await_error_codes' as async_error_codes;
 
 import 'dart:_js_embedded_names' show
     DEFERRED_LIBRARY_URIS,
@@ skipping 2266 matching lines @@
     // BoundClosure.prototype, respectively in pseudo JavaScript code. The
     // simplest way to access the JavaScript construction function of a Dart
     // class is to create an instance and access its constructor property.
     // Creating an instance ensures that any lazy class initialization has taken
     // place. The newly created instance could in theory be used directly as the
     // prototype, but it might include additional fields that we don't need.  So
     // we only use the new instance to access the constructor property and use
     // Object.create to create the desired prototype.
     //
     // TODO(sra): Perhaps cache the prototype to avoid the allocation.
-    var prototype = isStatic
-        ? JS('StaticClosure', 'Object.create(#.constructor.prototype)',
-             new StaticClosure())
-        : JS('BoundClosure', 'Object.create(#.constructor.prototype)',
-             new BoundClosure(null, null, null, null));
+    TearOffClosure dummyObject = isStatic
+        ? new StaticClosure()
+        : new BoundClosure(null, null, null, null);
+
+    var prototype = JS(
+        'TearOffClosure',
+        'Object.create(#.constructor.prototype)',
+        dummyObject);
 
     JS('', '#.\$initialize = #', prototype, JS('', '#.constructor', prototype));
     var constructor = isStatic
         ? JS('', 'function(){this.\$initialize()}')
         : isCsp
             ? JS('', 'function(a,b,c,d) {this.\$initialize(a,b,c,d)}')
             : JS('',
                  'new Function("a,b,c,d", "this.\$initialize(a,b,c,d);" + #)',
                  functionCounter++);
 
     // It is necessary to set the constructor property, otherwise it will be
     // "Object".
-    JS('', '#.constructor = #', prototype, constructor);
+    // We want the constructor.name property to have the name of the
+    // StaticClosure or BoundClosure class.
+    // Most browsers (except IE10) don't allow to change the name of a function
+    // as such we can't just set the property. However, we can work around this
+    // by creating an empty object with the name property set to the correct
+    // value and then setting the prototype to the original constructor.
+    // This works for all browsers except IE10 which doesn't have a way to
+    // change the prototype. There we simply set the name.
+    if (JS('bool', 'typeof Object.setPrototypeOf != "undefined"')) {
+      String tearOffClassName = JS('String', '#.constructor.name', dummyObject);
+      JS('', '#.constructor = {name: #}', prototype, tearOffClassName);
+      JS('', 'Object.setPrototypeOf(#.constructor, #)', prototype, constructor);
+    } else {
+      // IE10.
+      JS('', '#.constructor = #', prototype, constructor);
+      JS('', '#.constructor.name = #', prototype, propertyName);
+    }
 
     JS('', '#.prototype = #', constructor, prototype);
 
     // Create a closure and "monkey" patch it with call stubs.
     var trampoline = function;
     var isIntercepted = false;
     if (!isStatic) {
       if (JS('bool', '#.length == 1', jsArguments)) {
         // Intercepted call.
         isIntercepted = true;
@@ skipping 1814 matching lines @@
   // This is a function that will return a helper function that does the
   // iteration of the sync*.
   //
   // Each invocation should give a body with fresh state.
   final dynamic /* js function */ _outerHelper;
 
   SyncStarIterable(this._outerHelper);
 
   Iterator get iterator => new SyncStarIterator(JS('', '#()', _outerHelper));
 }