Enable getUserMedia to take constraints for its parameters.

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 89b0ec794cedbca914188cd13de5dc362af789ad..f995cf87c2bce337ae405698337045fec626e3ef 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -17386,11 +17386,22 @@ class Navigator native "*Navigator" {
    * Gets a stream (video and or audio) from the local computer.
    *
    * Use [MediaStream.supported] to check if this is supported by the current
-   * platform.
+   * platform. The arguments `audio` and `video` default to `false` (no
+   * constraints), but will accept Maps in each parameter to specify mandatory
+   * and optional constraints for the media stream. Not passing in a map, but 
+   * passing in `true` will provide a LocalMediaStream with audio or video 
+   * capabilities, but without any additional constraints.
    *
    * Example use:
    *
-   *     window.navigator.getUserMedia(audio:true, video: true).then((stream) {
+   *     window.navigator.getUserMedia(
+   *         audio: true, 
+   *         video: {'mandatory': 
+   *                    { 'minAspectRatio': 1.333, 'maxAspectRatio': 1.334 },
+   *                 'optional': 
+   *                    [{ 'minFrameRate': 60 },
+   *                     { 'maxWidth': 640 }]
+   *     }).then((stream) {
    *       var video = new VideoElement()
    *         ..autoplay = true
    *         ..src = Url.createObjectUrl(stream);
@@ -17403,15 +17414,15 @@ class Navigator native "*Navigator" {
   @DomName('Navigator.webkitGetUserMedia')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @Experimental
-  Future<LocalMediaStream> getUserMedia({bool audio: false,
-      bool video: false}) {
+  Future<LocalMediaStream> getUserMedia({audio: false,
+      video: false}) {
     var completer = new Completer<LocalMediaStream>();
     var options = {
       'audio': audio,
       'video': video
     };
     _ensureGetUserMedia();
-    this._getUserMedia(convertDartToNative_Dictionary(options),
+    this._getUserMedia(convertDartToNative_SerializedScriptValue(options),
       (stream) {
         completer.complete(stream);
       },