Add WebKit API for doing a hit-test that mimics GestureTap

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 3edee5b2c31858dee888e5985057244d9036c81d..de7d6d72229c7250b1f47f9262af7586f792b704 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -4066,6 +4066,18 @@ HitTestResult WebViewImpl::hitTestResultForWindowPos(const IntPoint& pos)
     return result;
 }
 
+WebHitTestResult WebViewImpl::hitTestResultForTap(const WebPoint& tapPointWindowPos, const WebSize& tapArea)
+{
+    // EventHandler does not care about the global position.

[hush (inactive), 2014/10/28 22:52:25]

What should be the correct global position here for gestureEvent?

[Rick Byers, 2014/11/04 06:09:19]

In the general tap case, the screen position can be passed through to JavaScript
(eg. as the MouseEvent.screen* properties).  In this case since you're doing
only a hit test, it should be completely unused.  I'd set it to 0,0 instead of
something that looks real.

Also strictly EventHandler does care (in the sense that it'll pass them
through), but the hit-testing phase doesn't.  So replace "EventHandler" with
"hit testing".

[hush (inactive), 2014/11/04 22:42:39]

Done

+    PlatformGestureEvent gestureEvent(PlatformEvent::GestureTap, IntPoint(tapPointWindowPos), IntPoint(tapPointWindowPos), IntSize(tapArea), 0, false, false, false, false, 0, 0, 0, 0);
+    if (!m_page->mainFrame()->isLocalFrame())
+        return HitTestResult();
+    HitTestResult result = m_page->deprecatedLocalMainFrame()->eventHandler().hitTestResultForGestureEvent(gestureEvent, HitTestRequest::ReadOnly | HitTestRequest::Active).hitTestResult();
+
+    result.setToShadowHostIfInUserAgentShadowRoot();

[hush (inactive), 2014/10/28 22:52:25]

Not sure about what this line does, but hitTestResultForWindowPos does this, so
I copied it here.

[Rick Byers, 2014/11/04 06:09:19]

You do want this.  It means, for example, that if a user taps on a form element,
you'll get the <input> element returned, not one of the hidden elements inside
of it used to implement <input> under the covers.

+    return result;
+}
+
 void WebViewImpl::setTabsToLinks(bool enable)
 {
     m_tabsToLinks = enable;