Add tests for Annex B extn: __proto__ in obj init (#633)

...annexB/language/expressions/object/__proto__-duplicate.js

...language/expressions/object/__proto__-value-non-object.js

...nnexB/language/expressions/object/__proto__-value-null.js

...annexB/language/expressions/object/__proto__-value-obj.js

...essions/assignment/destructuring/obj-prop-__proto__dup.js

test/language/expressions/object/__proto__-permitted-dup.js