Revert "dart2js cps: Maintain parent pointers instead of recomputing them."

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

Index: pkg/compiler/lib/src/cps_ir/insert_refinements.dart
diff --git a/pkg/compiler/lib/src/cps_ir/insert_refinements.dart b/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
index 327cd805d1fe448bf52b07a0decccb2c7631a128..149a4b360922f430b6ead15f366d4d0ec8cb61cc 100644
--- a/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
+++ b/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
@@ -4,11 +4,6 @@
 
 library cps_ir.optimization.insert_refinements;
 
-import 'optimizers.dart' show Pass;
-import 'shrinking_reductions.dart' show ParentVisitor;
-import 'cps_ir_nodes.dart';
-import '../types/constants.dart';
-import '../constants/values.dart';
 import '../common/names.dart';
 import '../types/types.dart' show
     TypeMask;
@@ -28,7 +23,7 @@ import 'type_mask_system.dart';
 ///
 /// Refinement nodes are inserted after a method invocation to refine the
 /// receiver to the types that can respond to the given selector.
-class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
+class InsertRefinements extends RecursiveVisitor implements Pass {
   String get passName => 'Insert refinement nodes';
 
   final TypeMaskSystem types;
@@ -39,6 +34,7 @@ class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
   InsertRefinements(this.types);
 
   void rewrite(FunctionDefinition node) {
+    new ParentVisitor().visit(node);
     visit(node.body);
   }
 
@@ -125,8 +121,7 @@ class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
     } else {
       // Filter away receivers that throw on this selector.
       TypeMask type = types.receiverTypeFor(node.selector, node.mask);
-      Refinement refinement = new Refinement(receiver, type);
-      pushRefinement(cont, refinement);
+      pushRefinement(cont, new Refinement(receiver, type));
     }
   }