Revert "Fix scope/context behavior in await transformer."

runtime/vm/parser.h

Index: runtime/vm/parser.h
diff --git a/runtime/vm/parser.h b/runtime/vm/parser.h
index 2946d7999cce77f2db238152bce7ac74833af8e8..3994aaae54d07806098d2c0be45074a6575cb279 100644
--- a/runtime/vm/parser.h
+++ b/runtime/vm/parser.h
@@ -773,10 +773,6 @@ class Parser : public ValueObject {
   // global variables.
   bool is_top_level_;
 
-  // await_is_keyword_ is true if we are parsing an async function. In this
-  // context async is not treated as identifier but as a keyword.
-  bool await_is_keyword_;
-
   // The member currently being parsed during "top level" parsing.
   MemberDesc* current_member_;