dart2js: Set the name to `null` for parameter stubs of static functions.

pkg/compiler/lib/src/js_emitter/model.dart

Index: pkg/compiler/lib/src/js_emitter/model.dart
diff --git a/pkg/compiler/lib/src/js_emitter/model.dart b/pkg/compiler/lib/src/js_emitter/model.dart
index 46b43196178df534057d660a73edf5c6d01b0658..fe06ef82c5975ac8736a889427b40a412ac77da1 100644
--- a/pkg/compiler/lib/src/js_emitter/model.dart
+++ b/pkg/compiler/lib/src/js_emitter/model.dart
@@ -367,6 +367,9 @@ abstract class Method {
   /// The element should only be used during the transition to the new model.
   /// Uses indicate missing information in the model.
   final Element element;
+  /// The name of the method. If the method is a [ParameterStubMethod] for a
+  /// static function, then the name can be `null`. In that case, only the
+  /// [ParameterStubMethod.callName] should be used.
   final js.Name name;
   final js.Expression code;