Refactor handling of unqualified static updates.

pkg/compiler/lib/src/resolution/registry.dart

 // Copyright (c) 2014, 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.
 
 library dart2js.resolution.registry;
 
 import '../common/backend_api.dart' show
     Backend;
 import '../common/registry.dart' show
     Registry;
@@ skipping 551 matching lines @@
     backend.resolutionCallbacks.onThrowExpression(this);
   }
 
   void registerDependency(Element element) {
     mapping.registerDependency(element);
   }
 
   Setlet<Element> get otherDependencies => mapping.otherDependencies;
 
   void registerStaticInvocation(Element element) {
+    // TODO(johnniwinther): Increase precision of [registerStaticUse] and
+    // [registerDependency].
     if (element == null) return;
     registerStaticUse(element);
     registerDependency(element);
   }
 
   void registerInstantiation(InterfaceType type) {
     world.registerInstantiatedType(type, this);
   }
 
   void registerAssert(Send node) {
@@ skipping 16 matching lines @@
   }
 
   void registerAsyncMarker(FunctionElement element) {
     backend.registerAsyncMarker(element, world, this);
   }
 
   void registerAsyncForIn(AsyncForIn node) {
     backend.resolutionCallbacks.onAsyncForIn(node, this);
   }
 }