[async await] fix async await desugaring

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 e1e3d3412281a274f2a3d03079735cc7c113a2de..3553b9fb1d17d44c28122773d43908030aeb2445 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -438,7 +438,7 @@ class ParserBase {
     }
 
     void set_promise_variable(typename Types::Variable* variable) {
-      DCHECK(variable != NULL);
+      DCHECK_NOT_NULL(variable);
       DCHECK(IsAsyncFunction(kind()));
       promise_variable_ = variable;
     }
@@ -446,6 +446,15 @@ class ParserBase {
       return promise_variable_;
     }
 
+    void set_async_return_variable(typename Types::Variable* variable) {
+      DCHECK_NOT_NULL(variable);
+      DCHECK(IsAsyncFunction(kind()));
+      async_return_variable_ = variable;
+    }
+    typename Types::Variable* async_return_variable() const {
+      return async_return_variable_;
+    }
+
     const ZoneList<DestructuringAssignment>&
         destructuring_assignments_to_rewrite() const {
       return destructuring_assignments_to_rewrite_;
@@ -515,6 +524,8 @@ class ParserBase {
     // For async functions, this variable holds a temporary for the Promise
     // being created as output of the async function.
     Variable* promise_variable_;
+    Variable* async_return_variable_;
+    Variable* is_rejection_variable_;
 
     FunctionState** function_state_stack_;
     FunctionState* outer_function_state_;
@@ -1518,6 +1529,8 @@ ParserBase<Impl>::FunctionState::FunctionState(
       expected_property_count_(0),
       generator_object_variable_(nullptr),
       promise_variable_(nullptr),
+      async_return_variable_(nullptr),
+      is_rejection_variable_(nullptr),
       function_state_stack_(function_state_stack),
       outer_function_state_(*function_state_stack),
       destructuring_assignments_to_rewrite_(16, scope->zone()),
@@ -4054,7 +4067,8 @@ void ParserBase<Impl>::ParseFunctionBody(
 
     // TODO(littledan): Merge the two rejection blocks into one
     if (IsAsyncFunction(kind)) {
-      init_block = impl()->BuildRejectPromiseOnException(init_block);
+      init_block =
+          impl()->BuildRejectPromiseOnExceptionForParameters(init_block);
     }
 
     inner_scope->set_end_position(scanner()->location().end_pos);