Make sure that parts of a date are returned as ints.

lib/compiler/implementation/ssa/codegen.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.
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
@@ skipping 2139 matching lines @@
     use(input);
     js.Expression or0 = new js.Binary("|", pop(), new js.LiteralNumber("0"));
     push(new js.Binary(cmp, left, or0));
   }
 
   void checkBigInt(HInstruction input, String cmp) {
     use(input);
     js.Expression left = pop();
     use(input);
     js.Expression right = pop();
-    // TODO(4984): Deal with infinity.
+    // TODO(4984): Deal with infinity and -0.0.
     push(new js.LiteralExpression.withData('Math.floor(#) === #',
                                            <js.Expression>[left, right]));
   }
 
   void checkTypeOf(HInstruction input, String cmp, String typeName) {
     use(input);
     js.Expression typeOf = new js.Prefix("typeof", pop());
     push(new js.Binary(cmp, typeOf, new js.LiteralString("'$typeName'")));
   }
 
@@ skipping 819 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }