Make RTC work on Firefox (mostly).

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 3bb3ec27a797671c48c9f6109aa6f4a086238033..ca7450733819c283cbdb7cf8509f694cf0251e5a 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -17286,7 +17286,10 @@ class RtcDtmfToneChangeEvent extends Event native "RTCDTMFToneChangeEvent" {
 @Experimental
 class RtcIceCandidate native "RTCIceCandidate" {
   factory RtcIceCandidate(Map dictionary) {
-    return JS('RtcIceCandidate', 'new RTCIceCandidate(#)',
+    var constructorName = JS('RtcIceCandidate', 'window[#]',
+        Device.isFirefox ? '${Device.propertyPrefix}RTCIceCandidate' : 

[blois, 2013/05/24 21:42:59]

Better to do something like:

new (window.RTCIceCandidate || window.mozRTCIceCandidate)();

This way it always uses the unprefixed when available.

Also, is it:
mozRTCIceCandidate
or:
MozRTCIceCandidate

[Emily Fortuna, 2013/05/24 22:40:54]

As discussed offline, this doesn't work because RTCIceCandidate is always
already defined, but you can only consturct the mozRTC.. version. I added a TODO
to get rid of the current code when it's saner in Firefox.

+        'RTCIceCandidate');
+    return JS('RtcIceCandidate', 'new #(#)', constructorName,
         convertDartToNative_SerializedScriptValue(dictionary));
   }
 
@@ -17346,9 +17349,12 @@ class RtcPeerConnection extends EventTarget native "RTCPeerConnection" {
     // Currently in Firefox some of the RTC elements are defined but throw an
     // error unless the user has specifically enabled them in their
     // about:config. So we have to construct an element to actually test if RTC
-    // is supported at at the given time.
+    // is supported at at the given time. Additionally, Firefox only supports IP
+    // numbers (currently), so we test with a random IP address.
+    // See https://bugzilla.mozilla.org/show_bug.cgi?id=837919 for details.
     try {
-      var c = new RtcPeerConnection({"iceServers": [ {"url":"stun:foo.com"}]});
+      var c = new RtcPeerConnection(
+          {"iceServers": [ {"url":"stun:216.93.246.18"}]});

[blois, 2013/05/24 21:42:59]

This feels very hacky for a supported check. Can we just check if the basic type
exists and tell people that they need to do further checks on their own?

[Emily Fortuna, 2013/05/24 22:40:54]

The deal is, the basic type always "exists" in firefox, even if it's not
"enabled" (see comment starting on line 17348).  It would be pretty confusing
and misleading to the user to claim that it's working, but then not actually
work. Because this doesn't have any side effects (aside from creating an object,
but it doesn't cause anything to "start happening"), and it's only going to be
called if someone is actually interested in using this functionality, I think it
is okay.

       return c is RtcPeerConnection;
     } catch (_) {}
     return false;
@@ -17633,8 +17639,6 @@ class RtcPeerConnection extends EventTarget native "RTCPeerConnection" {
   Stream<Event> get onSignalingStateChange => signalingStateChangeEvent.forTarget(this);
 
 }
-
-
 // Copyright (c) 2013, 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.
@@ -17645,7 +17649,11 @@ class RtcPeerConnection extends EventTarget native "RTCPeerConnection" {
 @Experimental
 class RtcSessionDescription native "RTCSessionDescription" {
   factory RtcSessionDescription(Map dictionary) {
-    return JS('RtcSessionDescription', 'new RTCSessionDescription(#)',
+    var constructorName = JS('RtcSessionDescription', 'window[#]',
+        Device.isFirefox ? '${Device.propertyPrefix}RTCSessionDescription' : 
+        'RTCSessionDescription');
+    return JS('RtcSessionDescription', 
+        'new #(#)', constructorName,

[blois, 2013/05/24 21:42:59]

Ditto from earlier comment.

         convertDartToNative_SerializedScriptValue(dictionary));
   }