Update invariant in class_members.dart.

dart/pkg/compiler/lib/src/resolution/class_members.dart

Index: dart/pkg/compiler/lib/src/resolution/class_members.dart
diff --git a/dart/pkg/compiler/lib/src/resolution/class_members.dart b/dart/pkg/compiler/lib/src/resolution/class_members.dart
index 7fd7edc321700678abd130ec76a726c0452d82f9..aaa40aa3707f472053433d66f0ab443547ce08d0 100644
--- a/dart/pkg/compiler/lib/src/resolution/class_members.dart
+++ b/dart/pkg/compiler/lib/src/resolution/class_members.dart
@@ -368,7 +368,10 @@ abstract class MembersCreator {
 
       DartType declaredType = declared.functionType;
       for (Member inherited in superMember.declarations) {
-        if (cls == inherited.declarer.element) {
+        if (inherited.element == declared.element) {
+          // TODO(ahe): For some reason, "call" elements are repeated in
+          // superMember.declarations. Investigate why.
+        } else if (cls == inherited.declarer.element) {
           // An error should already have been reported.
           assert(invariant(declared.element, compiler.compilationFailed));
           continue;