Add near calls (32-bit displacement) to Code objects on X64 platform.

src/mark-compact.cc

Index: src/mark-compact.cc
===================================================================
--- src/mark-compact.cc	(revision 3020)
+++ src/mark-compact.cc	(working copy)
@@ -282,8 +282,6 @@
            rinfo->IsCallInstruction());
     HeapObject* code = Code::GetCodeFromTargetAddress(rinfo->call_address());
     MarkCompactCollector::MarkObject(code);
-    // When compacting we convert the call to a real object pointer.
-    if (IsCompacting()) rinfo->set_call_object(code);
   }
 
  private:
@@ -1383,6 +1381,14 @@
         reinterpret_cast<Code*>(target)->instruction_start());
   }
 
+  void VisitDebugTarget(RelocInfo* rinfo) {
+    ASSERT(RelocInfo::IsJSReturn(rinfo->rmode()) && rinfo->IsCallInstruction());
+    Object* target = Code::GetCodeFromTargetAddress(rinfo->call_address());
+    VisitPointer(&target);
+    rinfo->set_call_address(
+        reinterpret_cast<Code*>(target)->instruction_start());
+  }
+
  private:
   void UpdatePointer(Object** p) {
     if (!(*p)->IsHeapObject()) return;