Generate better code for '=='.

pkg/dev_compiler/tool/input_sdk/private/js_array.dart

 // Copyright (c) 2012, 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.
 
 part of dart._interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
@@ skipping 523 matching lines @@
     if (!growable) markFixedList(list);
     return new JSArray<E>.typed(list);
   }
 
   Set<E> toSet() => new Set<E>.from(this);
 
   Iterator<E> get iterator => new ArrayIterator<E>(this);
 
   int get hashCode => Primitives.objectHashCode(this);
 
+  bool operator ==(other) => identical(this, other);
+
   int get length => JS('int', r'#.length', this);
 
   void set length(int newLength) {
     checkGrowable('set length');
     if (newLength is! int) {
       throw new ArgumentError.value(newLength, 'newLength');
     }
     // TODO(sra): Remove this test and let JavaScript throw an error.
     if (newLength < 0) {
       throw new RangeError.range(newLength, 0, null, 'newLength');
@@ skipping 74 matching lines @@
 
     if (_index >= length) {
       _current = null;
       return false;
     }
     _current = _iterable[_index];
     _index++;
     return true;
   }
 }