Small optimization for recursive calls: avoid dex cache.

Change-Id: I044757a2f06e535cdc1480c4fc8182b89635baf6
diff --git a/compiler/optimizing/code_generator_x86_64.h b/compiler/optimizing/code_generator_x86_64.h
index c30f4c2..dbdbf86 100644
--- a/compiler/optimizing/code_generator_x86_64.h
+++ b/compiler/optimizing/code_generator_x86_64.h
@@ -248,6 +248,7 @@
  private:
   // Labels for each block that will be compiled.
   GrowableArray<Label> block_labels_;
+  Label frame_entry_label_;
   LocationsBuilderX86_64 location_builder_;
   InstructionCodeGeneratorX86_64 instruction_visitor_;
   ParallelMoveResolverX86_64 move_resolver_;