Enable layout testing of the scroll animator.

Enable layout testing of the scroll animator.
https://bugs.webkit.org/show_bug.cgi?id=81858
Add a call to the InternalSettings that layout tests can use to
turn on scroll animation. Enable animation updates for the
Chromium platform DRT when scroll animation has been turned on in
a test. This should be a no-op for all current layout tests.

Patch by Scott Byer <scottbyer@chromium.org> on 2012-03-26
Reviewed by James Robinson.

Source/WebCore:

No new tests. Layout test results should be unchanged.

* testing/InternalSettings.cpp:
(WebCore::InternalSettings::setEnableScrollAnimator):
(WebCore):
(WebCore::InternalSettings::scrollAnimatorEnabled):
* testing/InternalSettings.h:
(InternalSettings):
* testing/InternalSettings.idl:

Source/WebKit/chromium:

* public/WebSettings.h:
* src/WebSettingsImpl.cpp:
(WebKit::WebSettingsImpl::scrollAnimatorEnabled):
(WebKit):
* src/WebSettingsImpl.h:
(WebSettingsImpl):

Tools:

* DumpRenderTree/chromium/WebViewHost.cpp:
(WebViewHost::serviceAnimation):
(WebViewHost::scheduleAnimation):
* DumpRenderTree/chromium/WebViewHost.h:
(WebViewHost):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@112196 268f45cc-cd09-0410-ab3c-d52691b4dbfc