Make invalid to override method names for local nested functions

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

Index: pkg/compiler/lib/src/resolution/members.dart
diff --git a/pkg/compiler/lib/src/resolution/members.dart b/pkg/compiler/lib/src/resolution/members.dart
index 652387b9ab146828326a32ce5cdb473311b9a15c..49d3c1ff589954e8e8cd4ecbafb37e9931b1fba6 100644
--- a/pkg/compiler/lib/src/resolution/members.dart
+++ b/pkg/compiler/lib/src/resolution/members.dart
@@ -2497,9 +2497,11 @@ class ResolverVisitor extends MappingVisitor<ResolutionResult> {
     } else {
       name = node.name.asIdentifier().source;
     }
+    Modifiers modifiers = node.name == null
+        ? Modifiers.EMPTY
+        : new Modifiers.withFlags(new NodeList.empty(), Modifiers.FLAG_FINAL);
     LocalFunctionElementX function = new LocalFunctionElementX(
-        name, node, ElementKind.FUNCTION, Modifiers.EMPTY,
-        enclosingElement);
+        name, node, ElementKind.FUNCTION, modifiers, enclosingElement);

[Johnni Winther, 2015/04/10 11:49:43]

The .isFinal property means 'declaratively final' which local functions are not.

Investigating the issue I found that actually handled assignment to functions
but failed on local functions (and super functions) for obscure reasons.

I've sent you a patch you can use.

Try adding tests for assignment to local functions as well super functions (like
`super.func = 42`) to the unittest `tests/compiler/dart2js/resolver_test.dart'
to test the patch.

[Siggi Cherem (dart-lang), 2015/04/11 00:12:21]

thanks, I was not very keen of this approach, but its good to confirm - from
working with analyzer, I am used to have some element synthesize information,
for example a getter with no setter implies a synthetic final variable. 
Thanks. I've updated this CL with your patch and the extra tests

     ResolverTask.processAsyncMarker(compiler, function, registry);
     function.functionSignatureCache = SignatureResolver.analyze(
         compiler,