Make invalid to override method names for local nested functions

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of resolution;
 
 abstract class TreeElements {
   AnalyzableElement get analyzedElement;
   Iterable<Node> get superUses;
 
@@ skipping 2993 matching lines @@
         }
         if (isComplex && getter == null && !inInstanceContext) {
           getter = reportAndCreateErroneousElement(node.selector, field.name,
               MessageKind.CANNOT_RESOLVE_GETTER, const {});
           registry.registerThrowNoSuchMethod();
         }
       } else if (target.impliesType) {
         setter = reportAndCreateErroneousElement(node.selector, target.name,
             MessageKind.ASSIGNING_TYPE, const {});
         registry.registerThrowNoSuchMethod();
-      } else if (target.isFinal ||
-                 target.isConst ||
-                 (target.isFunction &&
-                  Elements.isStaticOrTopLevelFunction(target) &&
-                  !target.isSetter)) {
-        if (target.isFunction) {
-          setter = reportAndCreateErroneousElement(node.selector, target.name,
-              MessageKind.ASSIGNING_METHOD, const {});
-        } else {
-          setter = reportAndCreateErroneousElement(node.selector, target.name,
-              MessageKind.CANNOT_RESOLVE_SETTER, const {});
-        }
+      } else if (target.isFinal || target.isConst) {
+        setter = reportAndCreateErroneousElement(
+              node.selector, target.name, MessageKind.CANNOT_RESOLVE_SETTER,
+              const {});
         registry.registerThrowNoSuchMethod();
+      } else if (target.isFunction && target.name != '[]=') {
+        assert(!target.isSetter);
+        setter = reportAndCreateErroneousElement(
+            node.selector, target.name, MessageKind.ASSIGNING_METHOD, const {});
+        registry.registerThrowNoSuchMethod();
+        if (node.isSuperCall) registry.registerSuperNoSuchMethod();
       }
       if (isPotentiallyMutableTarget(target)) {
         registry.registerPotentialMutation(target, node);
         if (enclosingElement != target.enclosingElement) {
           registry.registerPotentialMutationInClosure(target, node);
         }
         for (Node scope in promotionScope) {
           registry.registerPotentialMutationIn(scope, target, node);
         }
       }
@@ skipping 2076 matching lines @@
 }
 
 /// The result for the resolution of the `assert` method.
 class AssertResult implements ResolutionResult {
   const AssertResult();
 
   Element get element => null;
 
   String toString() => 'AssertResult()';
 }