dart2js cps: Fix bug in trampoline visitor.

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

 // Copyright (c) 2013, 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 dart2js.ir_nodes;
 
 import 'dart:collection';
 import '../constants/values.dart' as values;
 import '../dart_types.dart' show DartType, InterfaceType, TypeVariableType;
 import '../elements/elements.dart';
 import '../io/source_information.dart' show SourceInformation;
@@ skipping 2049 matching lines @@
     if (node.thisParameter != null) visit(node.thisParameter);
     node.parameters.forEach(visit);
     visit(node.returnContinuation);
     visit(node.body);
   }
 
   visitContinuation(Continuation cont) {
     if (cont.isReturnContinuation) {
       traverseContinuation(cont);
     } else {
-      _trampoline(traverseContinuation(cont));
+      int initialHeight = _stack.length;
+      Expression body = traverseContinuation(cont);
+      _trampoline(body, initialHeight: initialHeight);
     }
   }
 
   visitLetPrim(LetPrim node) => _trampoline(node);
   visitLetCont(LetCont node) => _trampoline(node);
   visitLetHandler(LetHandler node) => _trampoline(node);
   visitLetMutable(LetMutable node) => _trampoline(node);
 
   Expression traverseContinuation(Continuation cont) {
     processContinuation(cont);
@@ skipping 19 matching lines @@
     return node.body;
   }
 
   Expression traverseLetMutable(LetMutable node) {
     processLetMutable(node);
     visit(node.variable);
     processReference(node.value);
     return node.body;
   }
 
-  void _trampoline(Expression node) {
-    int initialHeight = _stack.length;
+  void _trampoline(Expression node, {int initialHeight}) {
+    initialHeight = initialHeight ?? _stack.length;
     _processBlock(node);
     while (_stack.length > initialHeight) {
       StackAction callback = _stack.removeLast();
       callback();
     }
   }
 
   _processBlock(Expression node) {
     while (node is InteriorExpression) {
       if (node is LetCont) {
@@ skipping 13 matching lines @@
 /// Visit a just-deleted subterm and unlink all [Reference]s in it.
 class RemovalVisitor extends TrampolineRecursiveVisitor {
   processReference(Reference reference) {
     reference.unlink();
   }
 
   static void remove(Node node) {
     (new RemovalVisitor()).visit(node);
   }
 }