Cache a pointer to V8DOMActivityLogger in PerContextData.
https://bugs.webkit.org/show_bug.cgi?id=112719

Patch by Ankur Taly <ataly@google.com> on 2013-03-19
Reviewed by Kentaro Hara.

Adds a data member (and getter, setter methods) to V8PerContextData
that holds a pointer to a V8DOMActivityLogger. This member is set while
initializing the context for a V8DOMWindowShell. Ownership of the pointer
is still retained by the HashMap in DOMWrapperWorld.
As a result of this patch, subsequent patches that will implement logging
for DOM API access (See bug 107207) will be able to obtain a reference to
the logger directly from PerContextData. This will benefit performance as it
will be faster than looking up the logger in the DOMActivityLoggerMap in
DOMWrapperWorld.

There are no new tests as there is no change in behavior.

* bindings/v8/V8DOMWindowShell.cpp:
(WebCore::V8DOMWindowShell::initializeIfNeeded):
* bindings/v8/V8PerContextData.h:
(WebCore::V8PerContextData::activityLogger):
(V8PerContextData):
(WebCore::V8PerContextData::setActivityLogger):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146295 268f45cc-cd09-0410-ab3c-d52691b4dbfc