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

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 91f3c9e2d632d8b20eee26627aadb35c1749b6a8..b9bad04078e0997ac8d233ba02725bb0081f9419 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -120,7 +120,7 @@ class HBasicBlock: public ZoneObject {
   void Goto(HBasicBlock* block, bool include_stack_check = false);
 
   int PredecessorIndexOf(HBasicBlock* predecessor) const;
-  void AddSimulate(int id) { AddInstruction(CreateSimulate(id)); }
+  void AddSimulate(AstId id) { AddInstruction(CreateSimulate(id)); }
   void AssignCommonDominator(HBasicBlock* other);
 
   // Add the inlined function exit sequence, adding an HLeaveInlined
@@ -155,7 +155,7 @@ class HBasicBlock: public ZoneObject {
   void RegisterPredecessor(HBasicBlock* pred);
   void AddDominatedBlock(HBasicBlock* block);
 
-  HSimulate* CreateSimulate(int id);
+  HSimulate* CreateSimulate(AstId id);
 
   int block_id_;
   HGraph* graph_;
@@ -478,7 +478,7 @@ class HEnvironment: public ZoneObject {
   Handle<JSFunction> closure() const { return closure_; }
 
   // ID of the original AST node to identify deoptimization points.
-  int ast_id() const { return ast_id_; }
+  AstId ast_id() const { return ast_id_; }
   void set_ast_id(int id) { ast_id_ = id; }
 
   const ZoneList<HValue*>* values() const { return &values_; }
@@ -545,7 +545,7 @@ class HEnvironment: public ZoneObject {
   HEnvironment* outer_;
   int pop_count_;
   int push_count_;
-  int ast_id_;
+  AstId ast_id_;
 };