Revert "Fix runtimeType.toString for tear-offs."

sdk/lib/_internal/js_runtime/lib/js_helper.dart

Index: sdk/lib/_internal/js_runtime/lib/js_helper.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/js_helper.dart b/sdk/lib/_internal/js_runtime/lib/js_helper.dart
index c39c6dc0131b3c33d7a26124eada257f6f2fd73d..291e1784bd851e8183963890355c0cf10ec4bf73 100644
--- a/sdk/lib/_internal/js_runtime/lib/js_helper.dart
+++ b/sdk/lib/_internal/js_runtime/lib/js_helper.dart
@@ -2283,14 +2283,11 @@ abstract class Closure implements Function {
     // Object.create to create the desired prototype.
     //
     // TODO(sra): Perhaps cache the prototype to avoid the allocation.
-    TearOffClosure dummyObject = isStatic
-        ? new StaticClosure()
-        : new BoundClosure(null, null, null, null);
-
-    var prototype = JS(
-        'TearOffClosure',
-        'Object.create(#.constructor.prototype)',
-        dummyObject);
+    var prototype = isStatic
+        ? JS('StaticClosure', 'Object.create(#.constructor.prototype)',
+             new StaticClosure())
+        : JS('BoundClosure', 'Object.create(#.constructor.prototype)',
+             new BoundClosure(null, null, null, null));
 
     JS('', '#.\$initialize = #', prototype, JS('', '#.constructor', prototype));
     var constructor = isStatic
@@ -2303,23 +2300,7 @@ abstract class Closure implements Function {
 
     // It is necessary to set the constructor property, otherwise it will be
     // "Object".
-    // 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('', '#.constructor = #', prototype, constructor);
 
     JS('', '#.prototype = #', constructor, prototype);