[JSC] CSSStyleDeclaration report incorrect descriptor
https://bugs.webkit.org/show_bug.cgi?id=89697

Reviewed by Benjamin Poulain.

Source/WebCore:

Change descriptor of CSSStyleDeclaration properties in order to have
writable and enumerable attributes set to true. Configurable is kept to
false since the property is not deleteable.

Test: fast/dom/CSSStyleDeclaration/cssstyledeclaration-properties-descriptor.html

* bindings/js/JSCSSStyleDeclarationCustom.cpp:
(WebCore::JSCSSStyleDeclaration::getOwnPropertySlotDelegate): Only set
DontDelete attribute when creating the descriptor for
CSSStyleDeclaration properties.

LayoutTests:

Add new test to check the descriptor of CSSStyleDeclaration properties.

* fast/dom/CSSStyleDeclaration/cssstyledeclaration-properties-descriptor-expected.txt: Added.
* fast/dom/CSSStyleDeclaration/cssstyledeclaration-properties-descriptor.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@167240 268f45cc-cd09-0410-ab3c-d52691b4dbfc