Make CompilerTask independent of compiler.

pkg/compiler/lib/src/enqueue.dart

Index: pkg/compiler/lib/src/enqueue.dart
diff --git a/pkg/compiler/lib/src/enqueue.dart b/pkg/compiler/lib/src/enqueue.dart
index f619520adef080da96da34cdac3c4a4add5f5534..29ae8ea4bf6c57ea145bff92b1a3d85aba559c2a 100644
--- a/pkg/compiler/lib/src/enqueue.dart
+++ b/pkg/compiler/lib/src/enqueue.dart
@@ -10,7 +10,7 @@ import 'common/codegen.dart' show CodegenWorkItem;
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show Resolution;
 import 'common/resolution.dart' show ResolutionWorkItem;
-import 'common/tasks.dart' show CompilerTask, DeferredAction, DeferredTask;
+import 'common/tasks.dart' show CompilerTask;
 import 'common/work.dart' show ItemCompilationContext, WorkItem;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
@@ -46,11 +46,13 @@ typedef ItemCompilationContext ItemCompilationContextCreator();
 class EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
+  final Compiler compiler;
 
   String get name => 'Enqueue';
 
   EnqueueTask(Compiler compiler)
-      : resolution = new ResolutionEnqueuer(
+      : compiler = compiler,
+        resolution = new ResolutionEnqueuer(
             compiler,
             compiler.backend.createItemCompilationContext,
             compiler.options.analyzeOnly && compiler.options.analyzeMain
@@ -60,7 +62,7 @@ class EnqueueTask extends CompilerTask {
             compiler,
             compiler.backend.createItemCompilationContext,
             const TreeShakingEnqueuerStrategy()),
-        super(compiler) {
+        super(compiler.measurer) {
     codegen.task = this;
     resolution.task = this;
 
@@ -714,11 +716,9 @@ class ResolutionEnqueuer extends Enqueuer {
 
   final Queue<ResolutionWorkItem> queue;
 
-  /**
-   * A deferred task queue for the resolution phase which is processed
-   * when the resolution queue has been emptied.
-   */
-  final Queue<DeferredTask> deferredTaskQueue;
+  /// Queue of deferred resolution actions to execute when the resolution queue
+  /// has been emptied.
+  final Queue<_DeferredAction> deferredQueue;
 
   static const ImpactUseCase IMPACT_USE =
       const ImpactUseCase('ResolutionEnqueuer');
@@ -733,7 +733,7 @@ class ResolutionEnqueuer extends Enqueuer {
             strategy),
         processedElements = new Set<AstElement>(),
         queue = new Queue<ResolutionWorkItem>(),
-        deferredTaskQueue = new Queue<DeferredTask>();
+        deferredQueue = new Queue<_DeferredAction>();
 
   bool get isResolutionQueue => true;
 
@@ -831,24 +831,26 @@ class ResolutionEnqueuer extends Enqueuer {
    *
    * The queue is processed in FIFO order.
    */
-  void addDeferredAction(Element element, DeferredAction action) {
+  void addDeferredAction(Element element, void action()) {
     if (queueIsClosed) {
       throw new SpannableAssertionFailure(
           element,
           "Resolution work list is closed. "
           "Trying to add deferred action for $element");
     }
-    deferredTaskQueue.add(new DeferredTask(element, action));
+    deferredQueue.add(new _DeferredAction(element, action));
   }
 
   bool onQueueEmpty(Iterable<ClassElement> recentClasses) {
-    emptyDeferredTaskQueue();
+    _emptyDeferredQueue();
     return super.onQueueEmpty(recentClasses);
   }
 
-  void emptyDeferredTaskQueue() {
-    while (!deferredTaskQueue.isEmpty) {
-      DeferredTask task = deferredTaskQueue.removeFirst();
+  void emptyDeferredQueueForTesting() => _emptyDeferredQueue();
+
+  void _emptyDeferredQueue() {
+    while (!deferredQueue.isEmpty) {
+      _DeferredAction task = deferredQueue.removeFirst();
       reporter.withCurrentElement(task.element, task.action);
     }
   }
@@ -1044,3 +1046,12 @@ class _EnqueuerImpactVisitor implements WorldImpactVisitor {
     enqueuer.registerTypeUse(typeUse);
   }
 }
+
+typedef void _DeferredActionFunction();
+
+class _DeferredAction {
+  final Element element;
+  final _DeferredActionFunction action;
+
+  _DeferredAction(this.element, this.action);
+}