pop of array hole should get from the prototype chain

pop of array hole should get from the prototype chain
https://bugs.webkit.org/show_bug.cgi?id=79338

Reviewed by Sam Weinig.

Source/JavaScriptCore:

* runtime/JSArray.cpp:
(JSC::JSArray::pop):
    - If the fast fast vector case fails, more closely follow the spec.

LayoutTests:

* sputnik/Conformance/15_Native_Objects/15.4_Array/15.4.4/15.4.4.6_Array_prototype_pop/S15.4.4.6_A4_T1-expected.txt:
    - Checking passing test result.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108650 268f45cc-cd09-0410-ab3c-d52691b4dbfc