Optional arguments in new compiler.

runtime/vm/flow_graph_compiler_x64.h

Index: runtime/vm/flow_graph_compiler_x64.h
===================================================================
--- runtime/vm/flow_graph_compiler_x64.h	(revision 5369)
+++ runtime/vm/flow_graph_compiler_x64.h	(working copy)
@@ -42,8 +42,6 @@
     Label label;
   };
 
-  int stack_local_count() const { return stack_local_count_; }
-  void set_stack_local_count(int count) { stack_local_count_ = count; }
   BlockEntryInstr* current_block() const { return current_block_; }
 
   // Bail out of the flow graph compiler.  Does not return to the caller.
@@ -99,6 +97,8 @@
 
   void GenerateInstantiatorTypeArguments(intptr_t token_index);
 
+  void CopyParameters();
+
   Assembler* assembler_;
   const ParsedFunction& parsed_function_;
   const GrowableArray<BlockEntryInstr*>* blocks_;
@@ -110,7 +110,6 @@
   BlockEntryInstr* current_block_;
 
   CodeGenerator::DescriptorList* pc_descriptors_list_;
-  int stack_local_count_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };