Make CompilerTask independent of compiler.

pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
index 29b516d7ecaca0248498c0e7d7aec515539d4773..18eeb525aae5d4bfee63c7ff83332f4c761430db 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
@@ -56,6 +56,7 @@ class ExplicitReceiverParameter implements Local {
 /// takes.
 class IrBuilderTask extends CompilerTask {
   final SourceInformationStrategy sourceInformationStrategy;
+  final Compiler compiler;
 
   String bailoutMessage = null;
 
@@ -65,7 +66,8 @@ class IrBuilderTask extends CompilerTask {
 
   IrBuilderTask(Compiler compiler, this.sourceInformationStrategy,
       [this.builderCallback])
-      : super(compiler);
+      : compiler = compiler,
+        super(compiler.measurer);
 
   String get name => 'CPS builder';
 
@@ -76,7 +78,7 @@ class IrBuilderTask extends CompilerTask {
 
       ResolvedAst resolvedAst = element.resolvedAst;
       element = element.implementation;
-      return reporter.withCurrentElement(element, () {
+      return compiler.reporter.withCurrentElement(element, () {
         SourceInformationBuilder sourceInformationBuilder =
             sourceInformationStrategy.createBuilderForContext(resolvedAst);