Disallow non-identifiers in for-in.

lib/compiler/implementation/resolver.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.
 
 abstract class TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   DartType getType(TypeAnnotation annotation);
   bool isParameterChecked(Element element);
 }
@@ skipping 2002 matching lines @@
         const SourceString('hasNext')]) {
       registerImplicitInvocation(name, 0);
     }
     visit(node.expression);
     Scope blockScope = new BlockScope(scope);
     Node declaration = node.declaredIdentifier;
     visitIn(declaration, blockScope);
     visitLoopBodyIn(node, node.body, blockScope);
 
     // TODO(lrn): Also allow a single identifier.
-    if ((declaration is !Send || declaration.asSend().selector is !Identifier)
+    if ((declaration is !Send || declaration.asSend().selector is !Identifier
+        || declaration.asSend().receiver != null)
         && (declaration is !VariableDefinitions ||
         !declaration.asVariableDefinitions().definitions.nodes.tail.isEmpty()))
     {
       // The variable declaration is either not an identifier, not a
       // declaration, or it's declaring more than one variable.
       error(node.declaredIdentifier, MessageKind.INVALID_FOR_IN, []);
     }
   }
 
   visitLabel(Label node) {
@@ skipping 1103 matching lines @@
     return result;
   }
   Element lookup(SourceString name) => localLookup(name);
   Element lexicalLookup(SourceString name) => localLookup(name);
 
   Element add(Element newElement) {
     throw "Cannot add an element in a patch library scope";
   }
   String toString() => 'PatchLibraryScope($origin,$patch)';
 }