Fix one crash in the compiler.

frog/leg/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   static final bool LOG_FAILURES = false;
 
@@ skipping 388 matching lines @@
 
     } else {
       Link<Type> argumentTypes = analyzeArguments(node.arguments);
       FunctionType funType;
       if (node.receiver !== null) {
         Type receiverType = analyze(node.receiver);
         if (receiverType === types.dynamicType) return types.dynamicType;
         if (receiverType === null) {
           fail(node.receiver, 'receivertype is null');
         }
+        if (receiverType.element.kind !== ElementKind.CLASS) {
+          fail(node.receiver, 'receivertype is not a class');
+        }
         ClassElement classElement = receiverType.element;
         // TODO(karlklose): substitute type arguments.
         Type memberType = lookupMethodType(node, classElement, selector.source);
         if (memberType === types.dynamicType) return types.dynamicType;
         if (memberType is !FunctionType) {
           fail(node, 'can only handle function types');
         }
         funType = memberType;
       } else {
         Element element = elements[node];
@@ skipping 256 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     fail(node);
   }
 
   visitTypedef(Typedef node) {
     fail(node);
   }
 }