Enable await in while and do-while.

runtime/vm/ast.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_AST_H_
 #define VM_AST_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
@@ skipping 940 matching lines @@
 
 class WhileNode : public AstNode {
  public:
   WhileNode(intptr_t token_pos,
             SourceLabel* label,
             AstNode* condition,
             SequenceNode* body)
     : AstNode(token_pos),
       label_(label),
       condition_(condition),
-      body_(body) {
+      body_(body),
+      condition_preamble_(NULL) {
     ASSERT(label_ != NULL);
     ASSERT(condition_ != NULL);
     ASSERT(body_ != NULL);
   }
 
   SourceLabel* label() const { return label_; }
   AstNode* condition() const { return condition_; }
   SequenceNode* body() const { return body_; }
+  SequenceNode* condition_preamble() const { return condition_preamble_; }
+
+  void set_condition_preamble(SequenceNode* condition_preamble) {
+    condition_preamble_ = condition_preamble;
+  }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
+    if (condition_preamble() != NULL) {
+      condition_preamble()->Visit(visitor);
+    }
     condition()->Visit(visitor);
     body()->Visit(visitor);
   }
 
   DECLARE_COMMON_NODE_FUNCTIONS(WhileNode);
 
  private:
   SourceLabel* label_;
   AstNode* condition_;
   SequenceNode* body_;
+  SequenceNode* condition_preamble_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(WhileNode);
 };
 
 
 class DoWhileNode : public AstNode {
  public:
   DoWhileNode(intptr_t token_pos,
               SourceLabel* label,
               AstNode* condition,
@@ skipping 906 matching lines @@
   const intptr_t try_index_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InlinedFinallyNode);
 };
 
 }  // namespace dart
 
 #undef DECLARE_COMMON_NODE_FUNCTIONS
 
 #endif  // VM_AST_H_