dart2dart Make sure we never create placeholder for Dynamic type.

lib/compiler/implementation/dart_backend/placeholder_collector.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 LocalPlaceholder implements Hashable {
   final String identifier;
   final Set<Node> nodes;
   LocalPlaceholder(this.identifier) : nodes = new Set<Node>();
   int hashCode() => identifier.hashCode();
   String toString() =>
@@ skipping 197 matching lines @@
 
   void makeNullPlaceholder(Node node) {
     assert(node is Identifier || node is Send);
     nullNodes.add(node);
   }
 
   void makeElementPlaceholder(Node node, Element element) {
     assert(element !== null);
     if (element === entryFunction) return;
     if (element.getLibrary() === coreLibrary) return;
+    if (element == compiler.types.dynamicType.element) {
+      internalError(
+          'Should never make element placeholder for dynamic type element',
+          node);
+    }
     elementNodes.putIfAbsent(element, () => new Set<Node>()).add(node);
   }
 
   void makePrivateIdentifier(Identifier node) {
     assert(node !== null);
     privateNodes.putIfAbsent(
         currentElement.getLibrary(), () => new Set<Identifier>()).add(node);
   }
 
   void makeUnresolvedPlaceholder(Node node) {
@@ skipping 88 matching lines @@
           final send = node.typeName.asSend();
           Identifier receiver = send.receiver;
           Identifier selector = send.selector;
           final hasPrefix = element is TypedefElement ||
               element.lookupConstructor(receiver.source, selector.source)
                   === null;
           if (!hasPrefix) target = send.receiver;
         }
       }
       // TODO(antonm): is there a better way to detect unresolved types?
-      if (type !== compiler.types.dynamicType) {
+      if (type.element !== compiler.types.dynamicType.element) {
         makeTypePlaceholder(target, type);
       } else {
         if (!isDynamicType(node)) makeUnresolvedPlaceholder(target);
       }
     }
     node.visitChildren(this);
   }
 
   visitVariableDefinitions(VariableDefinitions node) {
     // Collect only local placeholders.
@@ skipping 63 matching lines @@
       visit(node.defaultClause.typeArguments);
     }
   }
 
   visitTypedef(Typedef node) {
     assert(currentElement is TypedefElement);
     makeElementPlaceholder(node.name, currentElement);
     node.visitChildren(this);
   }
 }