RFC: Switch to ast ids (instead of positions) for type feedback.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 34316319aa3ebc61db008d7e663e27b2461fe0ed..582a0ca15290c5935c338728ce53a7a9a5044b7b 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -1017,9 +1017,9 @@ class HSimulate: public HInstruction {
 
   virtual void PrintDataTo(StringStream* stream) const;
 
-  bool HasAstId() const { return ast_id_ != AstNode::kNoNumber; }
-  int ast_id() const { return ast_id_; }
-  void set_ast_id(int id) {
+  bool HasAstId() const { return ast_id_ != kNoAstId; }
+  AstId ast_id() const { return ast_id_; }
+  void set_ast_id(AstId id) {
     ASSERT(!HasAstId());
     ast_id_ = id;
   }
@@ -1064,7 +1064,7 @@ class HSimulate: public HInstruction {
     // use lists are correctly updated.
     SetOperandAt(values_.length() - 1, value);
   }
-  int ast_id_;
+  AstId ast_id_;
   int pop_count_;
   int environment_height_;
   ZoneList<HValue*> values_;