[parsing] Fix context allocation for async functions.

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index 9f8c735f265c591555f8f95669de850ecb1cfde1..b0e72592922e47a60c04436324cf5eb8d69e0cfb 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -419,8 +419,9 @@ class ParserBase {
     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 {
@@ -4172,8 +4173,6 @@ void ParserBase<Impl>::ParseAsyncFunctionBody(Scope* scope, StatementListT body,
                                               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);