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

src/compiler.h

Index: src/compiler.h
diff --git a/src/compiler.h b/src/compiler.h
index 1176c6941a2c12fb029b0e082a4b6b293bc336c5..1e449b6472d1b2e5674040e52eebe410f04bc17f 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -59,7 +59,7 @@ class CompilationInfo BASE_EMBEDDED {
   v8::Extension* extension() const { return extension_; }
   ScriptDataImpl* pre_parse_data() const { return pre_parse_data_; }
   Handle<Context> calling_context() const { return calling_context_; }
-  int osr_ast_id() const { return osr_ast_id_; }
+  AstId osr_ast_id() const { return osr_ast_id_; }
 
   void MarkAsEval() {
     ASSERT(!is_lazy());
@@ -110,7 +110,7 @@ class CompilationInfo BASE_EMBEDDED {
   // Accessors for the different compilation modes.
   bool IsOptimizing() const { return mode_ == OPTIMIZE; }
   bool IsOptimizable() const { return mode_ == BASE; }
-  void SetOptimizing(int osr_ast_id) {
+  void SetOptimizing(AstId osr_ast_id) {
     SetMode(OPTIMIZE);
     osr_ast_id_ = osr_ast_id;
   }
@@ -192,7 +192,7 @@ class CompilationInfo BASE_EMBEDDED {
   // Compilation mode flag and whether deoptimization is allowed.
   Mode mode_;
   bool supports_deoptimization_;
-  int osr_ast_id_;
+  AstId osr_ast_id_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationInfo);
 };