dart2js: improve ssa utilization of bool value types

tests/compiler/dart2js/mock_libraries.dart

 // Copyright (c) 2014, 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 for creating mock versions of platform and internal libraries.
 
 library mock_libraries;
 
 String buildLibrarySource(
     Map<String, String> elementMap,
@@ skipping 329 matching lines @@
         operator %(other) => (this is JSInt) ? 42 : 42.2;
         operator <<(other) => _shlPositive(other);
         operator >>(other) {
           return _shrBothPositive(other) + _shrReceiverPositive(other) +
             _shrOtherPositive(other);
         }
         operator |(other) => 42;
         operator &(other) => 42;
         operator ^(other) => 42;
 
-        operator >(other) => true;
-        operator >=(other) => true;
-        operator <(other) => true;
-        operator <=(other) => true;
-        operator ==(other) => true;
+        operator >(other) => !identical(this, other);
+        operator >=(other) => !identical(this, other);
+        operator <(other) => !identical(this, other);
+        operator <=(other) => !identical(this, other);
+        operator ==(other) => identical(this, other);
         get hashCode => throw "JSNumber.hashCode not implemented.";
 
         // We force side effects on _tdivFast to mimic the shortcomings of
         // the effect analysis: because the `_tdivFast` implementation of
         // the core library has calls that may not already be analyzed,
         // the analysis will conclude that `_tdivFast` may have side
         // effects.
         _tdivFast(other) => new List()..length = 42;
         _shlPositive(other) => 42;
         _shrBothPositive(other) => 42;
@@ skipping 80 matching lines @@
 
     const LookupMap(this._entries, [this._nestedMaps = const []])
         : _key = null, _value = null;
 
     const LookupMap.pair(this._key, this._value)
         : _entries = const [], _nestedMaps = const [];
     V operator[](K k) => null;
   }''',
   '_version': 'const _version = "0.0.1+1";',
 };