Patch to enhance the source code line information for profiler.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
===================================================================
--- src/x64/lithium-x64.h	(revision 15927)
+++ src/x64/lithium-x64.h	(working copy)
@@ -210,7 +210,8 @@
   LInstruction()
       :  environment_(NULL),
          hydrogen_value_(NULL),
-         is_call_(false) { }
+         is_call_(false),
+         position_(RelocInfo::kNoPosition) { }
 
   virtual ~LInstruction() { }
 
@@ -250,6 +251,9 @@
   LPointerMap* pointer_map() const { return pointer_map_.get(); }
   bool HasPointerMap() const { return pointer_map_.is_set(); }
 
+  void set_position(int pos) { position_ = pos; }
+  int position() { return position_; }
+
   void set_hydrogen_value(HValue* value) { hydrogen_value_ = value; }
   HValue* hydrogen_value() const { return hydrogen_value_; }
 
@@ -291,6 +295,7 @@
   SetOncePointer<LPointerMap> pointer_map_;
   HValue* hydrogen_value_;
   bool is_call_;
+  int position_;
 };