Clean up ClosureMirror.invoke(#call, ...).

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index bb8b56ee864e6a2a9ee083a5916ab9c368db07f7..1eebbabf8cc20a03ff41c6875b8fe9b9326aae52 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -447,12 +447,13 @@ class _LocalClosureMirror extends _LocalInstanceMirror
   }
 
   // TODO(12602): Remove this special case.
-  delegate(Invocation invocation) {
-    if (invocation.isMethod && (invocation.memberName == #call)) {
-      return this.apply(invocation.positionalArguments,
-                        invocation.namedArguments).reflectee;
+  InstanceMirror invoke(Symbol memberName,
+                        List positionalArguments,
+                        [Map<Symbol, dynamic> namedArguments]) {
+    if (memberName == #call) {
+      return this.apply(positionalArguments, namedArguments);
     }
-    return super.delegate(invocation);
+    return super.invoke(memberName, positionalArguments, namedArguments);
   }
 
   InstanceMirror apply(List<Object> positionalArguments,