[parsing] Fix context allocation for async functions.

src/parsing/parser-base.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 401 matching lines @@
       next_materialized_literal_index_ += count;
     }
 
     void AddProperty() { expected_property_count_++; }
     int expected_property_count() { return expected_property_count_; }
 
     FunctionKind kind() const { return scope()->function_kind(); }
     FunctionState* outer() const { return outer_function_state_; }
 
     void set_generator_object_variable(typename Types::Variable* variable) {
-      DCHECK(variable != NULL);
+      DCHECK_NOT_NULL(variable);
       DCHECK(IsResumableFunction(kind()));
+      DCHECK(scope()->has_forced_context_allocation());
       generator_object_variable_ = variable;
     }
     typename Types::Variable* generator_object_variable() const {
       return generator_object_variable_;
     }
 
     void set_promise_variable(typename Types::Variable* variable) {
       DCHECK(variable != NULL);
       DCHECK(IsAsyncFunction(kind()));
       promise_variable_ = variable;
@@ skipping 3731 matching lines @@
   Expect(Token::RBRACE, CHECK_OK);
   return impl()->RewriteClassLiteral(name, &class_info, class_token_pos, ok);
 }
 
 template <typename Impl>
 void ParserBase<Impl>::ParseAsyncFunctionBody(Scope* scope, StatementListT body,
                                               FunctionKind kind,
                                               FunctionBodyType body_type,
                                               bool accept_IN, int pos,
                                               bool* ok) {
-  scope->ForceContextAllocation();
-
   impl()->PrepareAsyncFunctionBody(body, kind, pos);
 
   BlockT block = factory()->NewBlock(nullptr, 8, true, kNoSourcePosition);
 
   ExpressionT return_value = impl()->EmptyExpression();
   if (body_type == FunctionBodyType::kNormal) {
     ParseStatementList(block->statements(), Token::RBRACE,
                        CHECK_OK_CUSTOM(Void));
     return_value = factory()->NewUndefinedLiteral(kNoSourcePosition);
   } else {
@@ skipping 1316 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H