https://bugs.webkit.org/show_bug.cgi?id=87088

Reviewed by Geoff Garen.

r117859 introduced a preliminary implementation of ES6-like private name objects to JSC.
These are probably not yet ready to be web-facing, so disabling by default in WebCore.
Opting-in for JSC & DumpRenderTree so that we can still run the fast/js/names.html test.

Source/JavaScriptCore: 

* jsc.cpp:
(GlobalObject):
(GlobalObject::javaScriptExperimentsEnabled):
    - Implemented new trap to opt-in to private names support.
* runtime/JSGlobalObject.cpp:
(JSC):
(JSC::JSGlobalObject::reset):
    - Only add the Name property to the global object if experiments are enabled.
* runtime/JSGlobalObject.h:
(GlobalObjectMethodTable):
    - Added new trap to enabled experiments.
(JSGlobalObject):
(JSC::JSGlobalObject::finishCreation):
    - Set the global object's m_experimentsEnabled state on construction.
(JSC::JSGlobalObject::javaScriptExperimentsEnabled):
    - Defaults to off.

Source/WebCore: 

* WebCore.exp.in:
    - Added export.
* bindings/js/JSDOMWindowBase.cpp:
(WebCore):
(WebCore::JSDOMWindowBase::javaScriptExperimentsEnabled):
    - Override default from JSC, enable based on corresponding Setting.
* bindings/js/JSDOMWindowBase.h:
(JSDOMWindowBase):
    - Added declaration for javaScriptExperimentsEnabled. 
* page/Settings.cpp:
(WebCore::Settings::Settings):
(WebCore::Settings::setJavaScriptExperimentsEnabled):
(WebCore):
* page/Settings.h:
(Settings):
(WebCore::Settings::javaScriptExperimentsEnabled):
    - Added Setting, reflecting WebPreference.

Source/WebKit/mac: 

* WebView/WebPreferenceKeysPrivate.h:
* WebView/WebPreferences.mm:
(+[WebPreferences initialize]):
(-[WebPreferences setJavaScriptExperimentsEnabled:]):
(-[WebPreferences javaScriptExperimentsEnabled]):
* WebView/WebPreferencesPrivate.h:
* WebView/WebView.mm:
(-[WebView _preferencesChanged:]):
    - Added JavaScriptExperimentsEnabled to WebPreferences.

Source/WebKit2: 

* Shared/WebPreferencesStore.h:
(WebKit):
* UIProcess/API/C/WKPreferences.cpp:
(WKPreferencesSetJavaScriptExperimentsEnabled):
(WKPreferencesGetJavaScriptExperimentsEnabled):
* UIProcess/API/C/WKPreferences.h:
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::updatePreferences):
    - Added JavaScriptExperimentsEnabled to WebPreferences.

Tools: 

* DumpRenderTree/mac/DumpRenderTree.mm:
(resetDefaultsToConsistentValues):
    - Enable private name support in DRT.
* WebKitTestRunner/TestController.cpp:
(WTR::TestController::resetStateToConsistentValues):
    - Enable private name support in WKTR.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@118018 268f45cc-cd09-0410-ab3c-d52691b4dbfc