Fix dart2js int double test failure

tests/lib/profiler/metrics_num_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.
+//
 
+import 'dart:profiler';
 import 'package:expect/expect.dart';
 
-int main() {
-  var a = [1,2,3][2];
-  switch (a) {
-    case 0.0:            /// 01: compile-time error
-      print("illegal");  /// 01: continued
-    case 1:
-      print("OK");
-  }
-}
+testGaugeDouble() {
+  Expect.throws(() {
+    // max is not a double

[sra1, 2014/08/01 00:53:22]

I'm immediately sure what max is.
Maybe change these comments to say:
// `max` argument is not double.

+    gauge = new Gauge('test', 'alpha bravo', 1.0, 4);
+  });
+}
+
+main() {
+  testGaugeDouble();
+}