Return MaybeHandle from SetElement and DeleteElement.

src/json-parser.h

 // Copyright 2011 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 341 matching lines @@
 
         if (c0_ == '"') {
           // Successfully parsed index, parse and store element.
           AdvanceSkipWhitespace();
 
           if (c0_ != ':') return ReportUnexpectedCharacter();
           AdvanceSkipWhitespace();
           Handle<Object> value = ParseJsonValue();
           if (value.is_null()) return ReportUnexpectedCharacter();
 
-          JSObject::SetOwnElement(json_object, index, value, SLOPPY);
+          JSObject::SetOwnElement(json_object, index, value, SLOPPY).Assert();
           continue;
         }
         // Not an index, fallback to the slow path.
       }
 
       position_ = start_position;
 #ifdef DEBUG
       c0_ = '"';
 #endif
 
@@ skipping 424 matching lines @@
 
   ASSERT_EQ('"', c0_);
   // Advance past the last '"'.
   AdvanceSkipWhitespace();
   return result;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_PARSER_H_