Make CompilerTask independent of compiler.

tests/compiler/dart2js/type_checker_test.dart

Index: tests/compiler/dart2js/type_checker_test.dart
diff --git a/tests/compiler/dart2js/type_checker_test.dart b/tests/compiler/dart2js/type_checker_test.dart
index 0b3fb873e989ce1e2249ddb3cd83e4c8968a8a80..d471cf172fdd353a3b8c5c0f26e32344c60d7476 100644
--- a/tests/compiler/dart2js/type_checker_test.dart
+++ b/tests/compiler/dart2js/type_checker_test.dart
@@ -2563,14 +2563,14 @@ analyze(MockCompiler compiler,
     new CompilationUnitElementX(new Script(null, null, null), compiler.mainApp);
   Element function = new MockElement(compilationUnit);
   TreeElements elements = compiler.resolveNodeStatement(node, function);
-  compiler.enqueuer.resolution.emptyDeferredTaskQueue();
+  compiler.enqueuer.resolution.emptyDeferredQueueForTesting();
   TypeCheckerVisitor checker = new TypeCheckerVisitor(
       compiler, elements, compiler.types);
   DiagnosticCollector collector = compiler.diagnosticCollector;
   collector.clear();
   checker.analyze(node);
   if (flushDeferred) {
-    compiler.enqueuer.resolution.emptyDeferredTaskQueue();
+    compiler.enqueuer.resolution.emptyDeferredQueueForTesting();
   }
   compareWarningKinds(text, warnings, collector.warnings);
   compareWarningKinds(text, errors, collector.errors);