Add javascript compatibility warnings for integer values and integral double

tests/standalone/javascript_compatibility_warnings_test.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.
 
 // VMOptions=--warn_on_javascript_compatibility --no_warning_as_error --optimization_counter_threshold=5
 
 import "package:expect/expect.dart";
 
 f(x, y) {
-  // Unoptimized code.
+  // Unoptimized and optimized code.
   1 is double;  /// 00: ok
   if (1 is double) { x++; }  /// 01: ok
   try { 1 as double; } on CastError catch (e) { }  /// 02: ok
   try { var y = 1 as double; } on CastError catch (e) { }  /// 03: ok
   1.0 is int;  /// 04: ok
   if (1.0 is int) { x++; }  /// 05: ok
   try { 1.0 as int; } on CastError catch (e) { }  /// 06: ok
   try { var z = 1.0 as int; } on CastError catch (e) { }  /// 07: ok
 
   x is double;  /// 10: ok
@@ skipping 12 matching lines @@
   "$y";  /// 24: ok
   var z = "$y";  /// 25: ok
   y.toString();  /// 26: ok
   var z = y.toString();  /// 27: ok
 
   var a = "yz";
   var b = "xyz";
   b = b.substring(1);
   if (identical(a, b)) { }  /// 28: ok
 
+  if (identical(x, y)) { }  /// 29: ok
+  if (identical(y, x)) { }  /// 30: ok
+
   if (x > 10) {
     // Optimized code.
-    x is double;  /// 30: ok
-    if (x is double) { }  /// 31: ok
-    try { x as double; } on CastError catch (e) { }  /// 32: ok
-    try { var z = x as double; } on CastError catch (e) { }  /// 33: ok
-    y is int;  /// 34: ok
-    if (y is int) { }  /// 35: ok
-    try { y as int; } on CastError catch (e) { }  /// 36: ok
-    try { var z = y as int; } on CastError catch (e) { }  /// 37: ok
+    x is double;  /// 40: ok
+    if (x is double) { }  /// 41: ok
+    try { x as double; } on CastError catch (e) { }  /// 42: ok
+    try { var z = x as double; } on CastError catch (e) { }  /// 43: ok
+    y is int;  /// 44: ok
+    if (y is int) { }  /// 45: ok
+    try { y as int; } on CastError catch (e) { }  /// 46: ok
+    try { var z = y as int; } on CastError catch (e) { }  /// 47: ok
 
-    "${1.0}";  /// 40: ok
-    var z = "${1.0}";  /// 41: ok
-    (1.0).toString();  /// 42: ok
-    var z = (1.0).toString();  /// 43: ok
-    "$y";  /// 44: ok
-    var z = "$y";  /// 45: ok
-    y.toString();  /// 46: ok
-    var z = y.toString();  /// 47: ok
+    "${1.0}";  /// 50: ok
+    var z = "${1.0}";  /// 51: ok
+    (1.0).toString();  /// 52: ok
+    var z = (1.0).toString();  /// 53: ok
+    "$y";  /// 54: ok
+    var z = "$y";  /// 55: ok
+    y.toString();  /// 56: ok
+    var z = y.toString();  /// 57: ok
 
     var a = "yz";
     var b = "xyz";
     b = b.substring(1);
-    if (identical(a, b)) { }  /// 48: ok
+    if (identical(a, b)) { }  /// 58: ok
+
+    if (identical(x, y)) { }  /// 59: ok
+    if (identical(y, x)) { }  /// 60: ok
   }
 }
 
 g(x, y) => f(x, y);  // Test inlining calls.
 h(x, y) => g(x, y);
 
 main() {
   for (var i = 0; i < 20; i++) {
     h(i, i* 1.0);
   }
 }