Traverse newly discovered elements to pick more referenced types.

lib/compiler/implementation/dart_backend/backend.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 DartBackend extends Backend {
   final List<CompilerTask> tasks;
   final UnparseValidator unparseValidator;
 
   Map<Element, TreeElements> get resolvedElements() =>
       compiler.enqueuer.resolution.resolvedElements;
@@ skipping 51 matching lines @@
     Set<ClassElement> classes = new Set<ClassElement>();
     PlaceholderCollector collector = new PlaceholderCollector(compiler);
     resolvedElements.forEach((element, treeElements) {
       if (!shouldOutput(element)) return;
       if (element is AbstractFieldElement) return;
       collector.collect(element, treeElements);
       new ReferencedElementCollector(
           compiler, element, treeElements, typedefs, classes)
       .collect();
     });
+    final emptyTreeElements = new TreeElementMapping();
+    collectElement(element) { collector.collect(element, emptyTreeElements); }
+    typedefs.forEach(collectElement);
+    classes.forEach(collectElement);
 
     ConflictingRenamer renamer =
         new ConflictingRenamer(compiler, collector.placeholders);
     Emitter emitter = new Emitter(compiler, renamer);
     resolvedElements.forEach((element, treeElements) {
       if (!shouldOutput(element)) return;
       if (element.isMember()) {
         ClassElement enclosingClass = element.getEnclosingClass();
         assert(enclosingClass.isClass());
         assert(enclosingClass.isTopLevel());
@@ skipping 53 matching lines @@
   ReferencedElementCollector(
       this.compiler,
       this.element, this.treeElements,
       this.typedefs, this.classes);
 
   visitNode(Node node) { node.visitChildren(this); }
 
   visitTypeAnnotation(TypeAnnotation typeAnnotation) {
     final type = compiler.resolveTypeAnnotation(element, typeAnnotation);
     Element typeElement = type.element;
-    if (typeElement.isTypedef()) typedefs.add(typeElement);
+    if (typeElement.isTypedef() && !typedefs.contains(typeElement)) {
+      typedefs.add(typeElement);
+      new ReferencedElementCollector(
+          compiler, typeElement, new TreeElementMapping(), typedefs, classes)
+      .collect();
+    }
     if (typeElement.isClass()) classes.add(typeElement);
     typeAnnotation.visitChildren(this);
   }
 
   void collect() {
     element.parseNode(compiler).accept(this);
   }
 }