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..c77129ec0dcc04649b7111a71402e1ae4093ed23 100644
--- a/tools/dom/templates/html/dart2js/impl_URL.darttemplate
+++ b/tools/dom/templates/html/dart2js/impl_URL.darttemplate
@@ -6,10 +6,14 @@ part of $LIBRARYNAME;
 
 $(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);
+  static String createObjectUrl(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',