<rdar://problem/7197644> WebKit should broadcast an MSAA event when
jumping to a named anchor

https://bugs.webkit.org/show_bug.cgi?id=28899

Reviewed by Adam Roben.

WebKitTools:

* DumpRenderTree/AccessibilityController.cpp:
(logScrollingStartEventsCallback):
Turn on logging of scrolling start events.
(AccessibilityController::getJSClass):
Add a "logScrollingStartEvents" to the AccessibilityController's JS
class definition.
(AccessibilityController::resetToConsistentState):
Turn off logging of scrolling start events.

* DumpRenderTree/AccessibilityController.h:
Declare setLogScrollingStartEvents(). Add a member for the scrolling
start event hook.

* DumpRenderTree/mac/AccessibilityControllerMac.cpp:
(AccessibilityController::setLogScrollingStartEvents):
Stubbed.

* DumpRenderTree/win/AccessibilityControllerWin.cpp:
(AccessibilityController::AccessibilityController):
Initialize the handle to 0.
(logEventProc):
Renamed from logFocusEventProc; now logs scrolling start events, too.
Removed the assertion that the event is a focus event. Added a switch
to print a message for focus, scrolling start, and other, unknown
events.
(AccessibilityController::setLogFocusEvents):
Changed to use logEventProc.
(AccessibilityController::setLogScrollingStartEvents):
If turning logging off, unhook the scrolling start event hook, and clear
the member holding the handle. If turning on, query for the root
accessible, so that accessibility is enabled for the WebView, and call
SetWinEventHook to setup an event hook using logEventProc as the
callback function.

LayoutTests:

* platform/win/accessibility/scroll-to-anchor-expected.txt: Added.
* platform/win/accessibility/scroll-to-anchor.html:
Added. Turns on scrolling start event logging, then jumps to an
anchor at the bottom of the page.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@48368 268f45cc-cd09-0410-ab3c-d52691b4dbfc