Patch to enhance the source code line information for profiler.

src/x64/lithium-codegen-x64.h

Index: src/x64/lithium-codegen-x64.h
===================================================================
--- src/x64/lithium-codegen-x64.h	(revision 16062)
+++ src/x64/lithium-codegen-x64.h	(working copy)
@@ -67,7 +67,8 @@
         frame_is_built_(false),
         safepoints_(info->zone()),
         resolver_(this),
-        expected_safepoint_kind_(Safepoint::kSimple) {
+        expected_safepoint_kind_(Safepoint::kSimple),
+        old_position_(RelocInfo::kNoPosition) {
     PopulateDeoptimizationLiteralsWithInlinedFunctions();
   }
 
@@ -280,6 +281,7 @@
                                     int arguments,
                                     Safepoint::DeoptMode mode);
   void RecordPosition(int position);
+  void RecordAndUpdatePosition(int position);
 
   static Condition TokenToCondition(Token::Value op, bool is_unsigned);
   void EmitGoto(int block);
@@ -382,6 +384,8 @@
 
   Safepoint::Kind expected_safepoint_kind_;
 
+  int old_position_;
+
   class PushSafepointRegistersScope BASE_EMBEDDED {
    public:
     explicit PushSafepointRegistersScope(LCodeGen* codegen)