Patch to enhance the source code line information for profiler.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
===================================================================
--- src/x64/lithium-codegen-x64.cc	(revision 15927)
+++ src/x64/lithium-codegen-x64.cc	(working copy)
@@ -273,6 +273,9 @@
               instr->Mnemonic());
     }
 
+    int pos = instr->position();
+    if (pos >= 0) RecordPosition(pos);
+
     instr->CompileToNative(this);
   }
   EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());