Expand overloaded methods and optional parameters in the html library.

tools/dom/templates/html/dart2js/impl_URL.darttemplate

Index: tools/dom/templates/html/dart2js/impl_URL.darttemplate
diff --git a/tools/dom/templates/html/dart2js/impl_URL.darttemplate b/tools/dom/templates/html/dart2js/impl_URL.darttemplate
index 3da9a69527a8044d809703c90abbbcb3422f1e84..b7080de4c4dfdd8160ccee7000d4a2f288c2c3a9 100644
--- a/tools/dom/templates/html/dart2js/impl_URL.darttemplate
+++ b/tools/dom/templates/html/dart2js/impl_URL.darttemplate
@@ -9,7 +9,16 @@ $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   static String createObjectUrl(blob_OR_source_OR_stream) =>
       JS('String',
          '(self.URL || self.webkitURL).createObjectURL(#)',
-         blob_OR_source_OR_stream);
+          blob_OR_source_OR_stream);
+
+  static String createObjectUrlFromSource(MediaSource source) =>
+      JS('String', '(self.URL || self.webkitURL).createObjectURL(#)', source);
+  
+  static String createObjectUrlFromStream(MediaStream stream) =>
+      JS('String', '(self.URL || self.webkitURL).createObjectURL(#)', stream);
+  
+  static String createObjectUrlFromBlob(Blob blob) =>
+      JS('String', '(self.URL || self.webkitURL).createObjectURL(#)', blob);
 
   static void revokeObjectUrl(String url) =>
       JS('void',