Remove HNativeDebugInfo from start of basic blocks.

We do not require full environment at the start of basic block.
The dex pc contained in basic block is sufficient for line mapping.

Change-Id: I5ba9e5f5acbc4a783ad544769f9a73bb33e2bafa
diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index 360488e..fea87ab 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -532,6 +532,8 @@
   // artReadBarrierForRootSlow.
   void GenerateReadBarrierForRootSlow(HInstruction* instruction, Location out, Location root);
 
+  void GenerateNop();
+
  private:
   // Factored implementation of GenerateFieldLoadWithBakerReadBarrier
   // and GenerateArrayLoadWithBakerReadBarrier.