Bug 1556556 - Use FrameForPointOption::IsRelativeToLayoutViewport when passing layout-relative coordinates to GetFrameForPoint(). r=kats

Differential Revision: https://phabricator.services.mozilla.com/D71455

dom/events/ContentEventHandler.cpp

@@ -2552,7 +2552,9 @@ nsresult ContentEventHandler::OnQueryCharacterAtPoint(
   nsPoint ptInRoot = nsLayoutUtils::GetEventCoordinatesRelativeTo(
       &eventOnRoot, RelativeTo{rootFrame});
 
-  nsIFrame* targetFrame = nsLayoutUtils::GetFrameForPoint(rootFrame, ptInRoot);
+  nsIFrame* targetFrame = nsLayoutUtils::GetFrameForPoint(
+      rootFrame, ptInRoot,
+      {nsLayoutUtils::FrameForPointOption::IsRelativeToLayoutViewport});
   if (!targetFrame || !targetFrame->GetContent() ||
       !targetFrame->GetContent()->IsInclusiveDescendantOf(mRootContent)) {
     // There is no character at the point.

layout/base/PositionedEventTargeting.cpp

@@ -409,6 +409,9 @@ nsIFrame* FindFrameTargetedByInputEvent(
   if (aFlags & INPUT_IGNORE_ROOT_SCROLL_FRAME) {
     options += FrameForPointOption::IgnoreRootScrollFrame;
   }
+  if (aRootFrame.mViewportType == ViewportType::Layout) {
+    options += FrameForPointOption::IsRelativeToLayoutViewport;
+  }
   nsIFrame* target = nsLayoutUtils::GetFrameForPoint(
       aRootFrame.mFrame, aPointRelativeToRootFrame, options);
   PET_LOG(