Fixed warning causing drone.io to fail

lib/polymer_element.dart

Index: lib/polymer_element.dart
diff --git a/lib/polymer_element.dart b/lib/polymer_element.dart
index 76259d64692d420acc81a6d649c7721a83f425d5..ef9094e6e8a0e35cfb0be32a81009a27a8cdfe21 100644
--- a/lib/polymer_element.dart
+++ b/lib/polymer_element.dart
@@ -174,7 +174,7 @@ class PolymerElement extends CustomElement with _EventsMixin {
    * Using Polymer's platform/src/ShadowCSS.js passing the style tag's content.
    */
   void _shimCss(ShadowRoot root, String localName, String extendsName) {
-    var platform = js.context.Platform;
+    var platform = (js.context as dynamic).Platform;

[Jennifer Messerly, 2013/08/16 17:47:27]

eek, this is ugly!
can you add a TODO and refer to this bug:
https://code.google.com/p/dart/issues/detail?id=6111
 

[terry, 2013/08/16 17:55:34]

Do you think another solution is to change the signature of js.dart context
getter from

Proxy get context

to

get context

So it's untyped?  Wouldn't that solve this particular problem.

On 2013/08/16 17:47:27, John Messerly wrote:

[Jennifer Messerly, 2013/08/16 17:58:32]

in this case, yes. but it doesn't help with the general problem

[Siggi Cherem (dart-lang), 2013/08/16 18:13:06]

I believe you can also fix this by using this notation:

js.context["Platform"];

[Jennifer Messerly, 2013/08/16 18:17:56]

Yeah, the strange thing about that though is we are using dot notation later on
when we use platform, so it seems inconsistent.

Another workaround is:

    var context = js.context;
    var platform = context.Platform;

[terry, 2013/08/16 19:02:05]

Done.

My larger question is the TODO should go in js.dart with a temporary fix for the
context getter.  Then all downstream users of js interop aren't hitting this
ugliness.

On 2013/08/16 17:58:32, John Messerly wrote:

     if (platform == null) return;
     var shadowCss = platform.ShadowCSS;
     if (shadowCss == null) return;