Replace runTestCase with assert helpers [test/built-ins/Object]

test/built-ins/Object/getPrototypeOf/15.2.3.2-0-1.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-0-2.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-1-3.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-1-4.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-1.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-1.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-10.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-11.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-12.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-13.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-14.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-15.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-16.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-17.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-18.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-19.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-2.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-20.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-21.js

test/built-ins/Object/getPrototypeOf/15.2.3.2-2-22.js