Incremental compiler: support optional arguments.

dart/site/try/poi/poi.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 trydart.poi;
 
 import 'dart:async' show
     Completer,
     Future;
 
@@ skipping 520 matching lines @@
 }
 
 class ScriptOnlyFilter implements QueueFilter {
   final Uri script;
 
   ScriptOnlyFilter(this.script);
 
   bool checkNoEnqueuedInvokedInstanceMethods(Enqueuer enqueuer) => true;
 
   void processWorkItem(void f(WorkItem work), WorkItem work) {
-    if (work.element.library.canonicalUri == script) {
-      f(work);
-      printWallClock('Processed ${work.element}.');
-    } else {
-      printWallClock('Skipped ${work.element}.');
+    if (work.element.library.canonicalUri != script) {
+      // TODO(ahe): Rather nasty hack to work around another nasty hack in
+      // backend.dart. Find better solution.
+      if (work.element.name != 'closureFromTearOff') {
+        printWallClock('Skipped ${work.element}.');
+        return;
+      }
     }
+    f(work);
+    printWallClock('Processed ${work.element}.');
   }
 }
 
 class PoiTask extends CompilerTask {
   PoiTask(Compiler compiler) : super(compiler);
 
   String get name => 'POI';
 }