Fix conditionally parsing await as keyword.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index e2100454593513ff88c3821fd0702b90c74342f6..43d909f4e3af2f0b7a8f627314052ef065da7f46 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -286,6 +286,7 @@ Parser::Parser(const Script& script, const Library& library, intptr_t token_pos)
       token_kind_(Token::kILLEGAL),
       current_block_(NULL),
       is_top_level_(false),
+      await_is_keyword_(false),
       current_member_(NULL),
       allow_function_literals_(true),
       parsed_function_(NULL),
@@ -312,6 +313,7 @@ Parser::Parser(const Script& script,
       token_kind_(Token::kILLEGAL),
       current_block_(NULL),
       is_top_level_(false),
+      await_is_keyword_(false),
       current_member_(NULL),
       allow_function_literals_(true),
       parsed_function_(parsed_function),
@@ -3053,6 +3055,11 @@ SequenceNode* Parser::ParseFunc(const Function& func,
     OpenAsyncClosure();
   }
 
+  bool saved_await_is_keyword = await_is_keyword_;
+  if (func.IsAsyncFunction() || func.is_async_closure()) {
+    await_is_keyword_ = true;
+  }
+
   intptr_t end_token_pos = 0;
   if (CurrentToken() == Token::kLBRACE) {
     ConsumeToken();
@@ -3121,6 +3128,7 @@ SequenceNode* Parser::ParseFunc(const Function& func,
   current_block_->statements->Add(body);
   innermost_function_ = saved_innermost_function.raw();
   last_used_try_index_ = saved_try_index;
+  await_is_keyword_ = saved_await_is_keyword;
   return CloseBlock();
 }
 
@@ -6353,7 +6361,7 @@ bool Parser::IsSimpleLiteral(const AbstractType& type, Instance* value) {
 
 // Returns true if the current token is kIDENT or a pseudo-keyword.
 bool Parser::IsIdentifier() {
-  return Token::IsIdentifier(CurrentToken());
+  return Token::IsIdentifier(CurrentToken()) && !IsAwaitAsKeyword();
 }
 
 
@@ -8002,6 +8010,12 @@ bool Parser::IsLiteral(const char* literal) {
 }
 
 
+bool Parser::IsAwaitAsKeyword() {
+  return await_is_keyword_ &&
+         (CurrentLiteral()->raw() == Symbols::Await().raw());
+}
+
+
 static bool IsIncrementOperator(Token::Kind token) {
   return token == Token::kINCR || token == Token::kDECR;
 }
@@ -10939,9 +10953,7 @@ AstNode* Parser::ParsePrimary() {
     OpenBlock();
     primary = ParseFunctionStatement(true);
     CloseBlock();
-  } else if (IsLiteral("await") &&
-             (parsed_function()->function().IsAsyncFunction() ||
-              parsed_function()->function().is_async_closure())) {
+  } else if (IsAwaitAsKeyword()) {
     // The body of an async function is parsed multiple times. The first time
     // when setting up an AsyncFunction() for generating relevant scope
     // information. The second time the body is parsed for actually generating