[assembler] Remove unnecessary cast.

src/x64/assembler-x64-inl.h

Index: src/x64/assembler-x64-inl.h
diff --git a/src/x64/assembler-x64-inl.h b/src/x64/assembler-x64-inl.h
index 2760df73432f66e84c82250b61eb5d621caaebd8..6001dc5e0e3cc3a745f2db1b95f459c7abe54a2b 100644
--- a/src/x64/assembler-x64-inl.h
+++ b/src/x64/assembler-x64-inl.h
@@ -514,9 +514,9 @@ void RelocInfo::set_debug_call_address(Address target) {
                          pc_ + Assembler::kPatchDebugBreakSlotAddressOffset,
                          sizeof(Address));
   if (host() != NULL) {
-    Object* target_code = Code::GetCodeFromTargetAddress(target);
-    host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
-        host(), this, HeapObject::cast(target_code));
+    Code* target_code = Code::GetCodeFromTargetAddress(target);
+    host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(host(), this,
+                                                                  target_code);
   }
 }