Traverse newly discovered elements to pick more referenced types.

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 SendVisitor extends ResolvedVisitor {
   final PlaceholderCollector collector;
 
   SendVisitor(this.collector, TreeElements elements) : super(elements);
 
   visitSuperSend(Send node) {}
@@ skipping 127 matching lines @@
     if (element is FunctionElement) {
       currentElement = element;
       elementNode = currentElement.parseNode(compiler);
       collectFunctionDeclarationPlaceholders(element, elementNode);
     } else if (element.isField()) {
       // TODO(smok): In the future make sure we don't process same
       // variable list element twice, better merge this with emitter logic.
       currentElement = element.variables;
       elementNode = currentElement.parseNode(compiler);
       collectFieldDeclarationPlaceholders(element, elementNode);
+    } else if (element is ClassElement || element is TypedefElement) {
+      currentElement = element;
+      elementNode = currentElement.parseNode(compiler);
     } else {
       assert(false); // Unreachable.
     }
     elementNode.accept(this);
   }
 
   Type resolveType(TypeAnnotation typeAnnotation) {
     if (treeElements === null) return null;
     var result = treeElements.getType(typeAnnotation);
     // TODO: Have better type resolution.
@@ skipping 27 matching lines @@
   }
 
   void internalError(String reason, [Node node]) {
     compiler.cancel(reason: reason, node: node);
   }
 
   visit(Node node) => (node === null) ? null : node.accept(this);
 
   visitNode(Node node) { node.visitChildren(this); }  // We must go deeper.
 
-  visitClassNode(ClassNode node) {
-    internalError('Should never meet ClassNode', node);
-  }
-
   visitSend(Send send) {
     new SendVisitor(this, treeElements).visitSend(send);
     send.visitChildren(this);
   }
 
   visitSendSet(SendSet send) {
     final element = treeElements[send];
     if (element !== null && element.isInstanceMember()) {
       tryMakePrivateIdentifier(send.selector.asIdentifier());
     }
@@ skipping 10 matching lines @@
         final send = node.typeName.asSend();
         final hasPrefix = element.lookupConstructor(
           send.receiver.source, send.selector.source) === null;
         if (!hasPrefix) target = send.receiver;
       }
     }
     makeTypePlaceholder(target, type);
     node.visitChildren(this);
   }
 }