Implement elementsFromPoint

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 2e1ad22b19633d99bfdc6c0ecb6bc4a3e7812ebd..b4104a06c3fa1ba6c310c9ab80fe3d9c5a1ede7a 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -1050,6 +1050,8 @@ WebRect WebViewImpl::computeBlockBounds(const WebRect& rect, bool ignoreClipping
     // Use the rect-based hit test to find the node.
     IntPoint point = mainFrameImpl()->frameView()->windowToContents(IntPoint(rect.x, rect.y));
     HitTestRequest::HitTestRequestType hitType = HitTestRequest::ReadOnly | HitTestRequest::Active | (ignoreClipping ? HitTestRequest::IgnoreClipping : 0);
+    // crbug.com/451914: This does not look correct: we're using a list-based
+    // hit test but only using the single element result.
     HitTestResult result = mainFrameImpl()->frame()->eventHandler().hitTestResultAtPoint(point, hitType, LayoutSize(rect.width, rect.height));
     result.setToShadowHostIfInUserAgentShadowRoot();