Revert r23380, some browser tests fail.

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

Index: sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/lib/js_helper.dart	(revision 23381)
+++ sdk/lib/_internal/compiler/implementation/lib/js_helper.dart	(working copy)
@@ -145,13 +145,13 @@
   static int hashCodeSeed = 0;
 
   static int objectHashCode(object) {
-    int hash = JS('int|Null', r'#.$identityHash', object);
+    int hash = JS('var', r'#.$identityHash', object);
     if (hash == null) {
       // TOOD(ahe): We should probably randomize this somehow.
       hash = ++hashCodeSeed;
       JS('void', r'#.$identityHash = #', object, hash);
     }
-    return JS('int', '#', hash);
+    return hash;
   }
 
   /**
@@ -946,28 +946,6 @@
   String toString() => "Closure";
 }
 
-class BoundClosure extends Closure {
-  var self;
-  var target;
-  var receiver;
-
-  bool operator==(other) {
-    if (identical(this, other)) return true;
-    if (other is! BoundClosure) return false;
-    return JS('bool', '# === # && # === # && # === #',
-        self, other.self,
-        target, other.target,
-        receiver, other.receiver);
-  }
-
-  int get hashCode {
-    return JS('int', '(# + # + #) & 0x3ffffff',
-        self.hashCode,
-        target.hashCode,
-        receiver.hashCode);
-  }
-}
-
 bool jsHasOwnProperty(var jsObject, String property) {
   return JS('bool', r'#.hasOwnProperty(#)', jsObject, property);
 }