Add javascript compatibility warnings for integer values and integral double

tests/standalone/javascript_compatibility_errors_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 --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: compile-time error
   if (1 is double) { x++; }  /// 01: compile-time error
   try { 1 as double; } on CastError catch (e) { }  /// 02: compile-time error
   try { var y = 1 as double; } on CastError catch (e) { }  /// 03: compile-time error
   1.0 is int;  /// 04: compile-time error
   if (1.0 is int) { x++; }  /// 05: compile-time error
   try { 1.0 as int; } on CastError catch (e) { }  /// 06: compile-time error
   try { var z = 1.0 as int; } on CastError catch (e) { }  /// 07: compile-time error
 
   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
 
-    "${1.0}";  /// 40: compile-time error
-    var z = "${1.0}";  /// 41: compile-time error
-    (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
+    "${1.0}";  /// 50: compile-time error
+    var z = "${1.0}";  /// 51: compile-time error
+    (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
   }
 }
 
 k(x, y) {
-  // Unoptimized code.
+  // Unoptimized and optimized code.
   1.5 is double;
   if (1.5 is double) { x++; }
   try { 1.5 as double; } on CastError catch (e) { }
   try { var y = 1.5 as double; } on CastError catch (e) { }
   1.5 is int;
   if (1.5 is int) { x++; }
   try { 1.5 as int; } on CastError catch (e) { }
   try { var z = 1.5 as int; } on CastError catch (e) { }
 
   1.5 is double;
@@ skipping 16 matching lines @@
 
   "${1.5}";
   var z = "${1.5}";
   (1.5).toString();
   z = (1.5).toString();
   "$y";
   z = "$y";
   y.toString();
   z = y.toString();
 
+  var a = "xyz";
+  var b = "xyz";
+  b = b.substring(1);
+  if (identical(a, b)) { }
+
+  if (identical(x, y)) { }
+  if (identical(y, x)) { }
+
   if (x > 10) {
     // Optimized code.
     x is double;
     if (x is double) { }
     try { x as double; } on CastError catch (e) { }
     try { var z = x as double; } on CastError catch (e) { }
     y is int;
     if (y is int) { }
     try { y as int; } on CastError catch (e) { }
     try { var z = y as int; } on CastError catch (e) { }
 
     "${1.5}";
     var z = "${1.5}";
     (1.5).toString();
     z = (1.5).toString();
     "$y";
     z = "$y";
     y.toString();
     z = y.toString();
+
+    var a = "xyz";
+    var b = "xyz";
+    b = b.substring(1);
+    if (identical(a, b)) { }
+
+    if (identical(x, y)) { }
+    if (identical(y, x)) { }
   }
 }
 
 g(x, y) => f(x, y);  // Test inlining calls.
 h(x, y) => g(x, y);
 
 // We don't test for _JavascriptCompatibilityError since it's not visible.
 // It should not be visible since it doesn't exist on dart2js.
 bool isJavascriptCompatibilityError(e) =>
     e is Error && "$e".contains("Javascript Compatibility Error");
 
 main() {
   // Since the warning (or error in case of --warning_as_error) is issued at
   // most once per location, the Expect.throw must guard the whole loop.
   Expect.throws(
       () {
         for (var i = 0; i < 20; i++) {
           h(i, i * 1.0);
         }
       },
       isJavascriptCompatibilityError);
 
   // No warnings (errors) should be issued after this point.
   for (var i = 0; i < 20; i++) {
     k(i * 1.0, i);
     k(i * 1.0, i + 0.5);
   }
 }