Return MaybeHandle from NewConsString.

src/json-stringifier.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 483 matching lines @@
     SerializeDeferredKey(deferred_comma, key);
   }
 
   Handle<String> result_string = Handle<String>::cast(result);
   // Shrink current part, attach it to the accumulator, also attach the result
   // string to the accumulator, and allocate a new part.
   ShrinkCurrentPart();  // Shrink.
   part_length_ = kInitialPartLength;  // Allocate conservatively.
   Extend();             // Attach current part and allocate new part.
   // Attach result string to the accumulator.
-  Handle<String> cons = factory_->NewConsString(accumulator(), result_string);
-  RETURN_IF_EMPTY_HANDLE_VALUE(isolate_, cons, EXCEPTION);
+  Handle<String> cons;
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate_, cons,
+      factory_->NewConsString(accumulator(), result_string),
+      EXCEPTION);
   set_accumulator(cons);
   return SUCCESS;
 }
 
 
 BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSValue(
     Handle<JSValue> object) {
   bool has_exception = false;
   String* class_name = object->class_name();
   if (class_name == isolate_->heap()->String_string()) {
@@ skipping 208 matching lines @@
                                       current_index_);
 }
 
 
 void BasicJsonStringifier::Accumulate() {
   if (accumulator()->length() + current_part_->length() > String::kMaxLength) {
     // Screw it.  Simply set the flag and carry on.  Throw exception at the end.
     set_accumulator(factory_->empty_string());
     overflowed_ = true;
   } else {
-    set_accumulator(factory_->NewConsString(accumulator(), current_part_));
+    set_accumulator(factory_->NewConsString(accumulator(),
+                                            current_part_).ToHandleChecked());
   }
 }
 
 
 void BasicJsonStringifier::Extend() {
   Accumulate();
   if (part_length_ <= kMaxPartLength / kPartLengthGrowthFactor) {
     part_length_ *= kPartLengthGrowthFactor;
   }
   if (is_ascii_) {
@@ skipping 132 matching lines @@
       SerializeString_<false, uint8_t>(object);
     } else {
       SerializeString_<false, uc16>(object);
     }
   }
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_STRINGIFIER_H_