Add TypeUse.

pkg/compiler/lib/src/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.
 
 part of dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
@@ skipping 346 matching lines @@
 
   @override
   WorldImpact transformResolutionImpact(ResolutionImpact worldImpact) {
     TransformedWorldImpact transformed =
         new TransformedWorldImpact(worldImpact);
     for (DartType typeLiteral in worldImpact.typeLiterals) {
       if (typeLiteral.isInterfaceType) {
         backend.usedTypeLiterals.add(typeLiteral.element);
       }
     }
-    for (InterfaceType instantiatedType in worldImpact.instantiatedTypes) {
-      // TODO(johnniwinther): Remove this when dependency tracking is done on
-      // the world impact itself.
-      transformed.registerInstantiatedType(instantiatedType);
-      backend.registerPlatformMembers(instantiatedType,
-          registerUse: transformed.registerDynamicUse);
+    for (TypeUse typeUse in worldImpact.typeUses) {
+      if (typeUse.kind == TypeUseKind.INSTANTIATION) {
+        backend.registerPlatformMembers(typeUse.type,
+            registerUse: transformed.registerDynamicUse);
+      }
     }
     return transformed;
   }
 }
 
 class EmitterUnparser extends Unparser {
   final Map<Node, String> renames;
 
   EmitterUnparser(this.renames, {bool minify, bool stripTypes})
       : super(minify: minify, stripTypes: stripTypes);
@@ skipping 166 matching lines @@
   }
 
   // TODO(johnniwinther): Remove this when values are computed from the
   // expressions.
   @override
   void copyConstantValues(DartConstantTask task) {
     constantCompiler.constantValueMap.addAll(
         task.constantCompiler.constantValueMap);
   }
 }