Simplify restoring of saved try contexts in async code by passing around the

runtime/vm/parser.h

Index: runtime/vm/parser.h
===================================================================
--- runtime/vm/parser.h	(revision 45079)
+++ runtime/vm/parser.h	(working copy)
@@ -628,11 +628,12 @@
   void PushTry(Block* try_block);
   // Pop the inner most try block from the stack.
   TryStack* PopTry();
-  // Collect try block scopes and indices if await or yield is in try block.
-  void CheckAsyncOpInTryBlock(LocalScope** try_scope,
-                              int16_t* try_index,
-                              LocalScope** outer_try_scope,
-                              int16_t* outer_try_index) const;
+  // Collect saved try context variables if await or yield is in try block.
+  void CheckAsyncOpInTryBlock(
+      LocalVariable** saved_try_ctx,
+      LocalVariable** async_saved_try_ctx,
+      LocalVariable** outer_saved_try_ctx,
+      LocalVariable** outer_async_saved_try_ctx) const;
   // Add specified node to try block list so that it can be patched with
   // inlined finally code if needed.
   void AddNodeForFinallyInlining(AstNode* node);