Fix __proto__ parsing in object literals (#3704)

Co-authored-by: Rafal Walczyna r.walczyna@samsung.com
JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

tests/jerry/es2015/object-prototype-proto.js

@@ -26,7 +26,7 @@ var o = {};
 o.__proto__ = Array.prototype;
 assert(o instanceof Array);
 
-var obj = Object.create(null) 
+var obj = Object.create(null)
 p = {};
 obj.__proto__ = p;
 assert(Object.getPrototypeOf(obj) !== p);
@@ -54,5 +54,36 @@ try {
   assert(e instanceof TypeError);
 }
 
-var o2 =  { ["__proto__"] : null };
+var o2 = { ["__proto__"] : null };
 assert(o2.__proto__ === null);
+assert(Object.getPrototypeOf(o2) === Object.prototype);
+
+var o3 = { __proto__ : null };
+assert(o3.__proto__ === undefined);
+assert(Object.getPrototypeOf(o3) === null);
+
+var o4 = { "__proto__" : null };
+assert(o4.__proto__ === undefined);
+assert(Object.getPrototypeOf(o4) === null);
+
+var __proto__ = [];
+var o5 = { __proto__ };
+assert(o5.__proto__ === __proto__);
+assert(Object.getPrototypeOf(o5) === Object.prototype);
+
+var o6 = { __proto__() { return "42" } };
+assert(o6.__proto__() === "42");
+assert(Object.getPrototypeOf(o6) === Object.prototype);
+
+var o7 = { __\u0070r\u006ft\u006f__: null };
+assert(o7.__proto__ === undefined);
+assert(Object.getPrototypeOf(o7) === null);
+
+var o8 = { };
+o8.__proto__ = Array.prototype;
+assert(Object.getPrototypeOf(o8) === Array.prototype);
+
+var str1 = '{"__proto__": [] }';
+var obj1 = JSON.parse(str1);
+assert(Object.getPrototypeOf(obj1) === Object.prototype);
+assert(Array.isArray(obj1.__proto__));