Rework compositor touch hit testing

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index f535ada36d9386c241ee0a911d7a57fa61946066..9b9b68aeeb3658cc758d8bc98d7285e5385a0edb 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -7340,6 +7340,22 @@ void RenderBlock::addFocusRingRects(Vector<IntRect>& rects, const LayoutPoint& a
         inlineElementContinuation()->addFocusRingRects(rects, flooredLayoutPoint(additionalOffset + inlineElementContinuation()->containingBlock()->location() - location()), paintContainer);
 }
 
+void RenderBlock::computeOwnHitTestRects(Vector<IntRect>& rects, const LayoutPoint& layerOffset) const
+{
+    RenderBox::computeOwnHitTestRects(rects, layerOffset);
+
+    if (hasHorizontalLayoutOverflow() || hasVerticalLayoutOverflow()) {
+        for (RootInlineBox* curr = firstRootBox(); curr; curr = curr->nextRootBox()) {
+            LayoutUnit top = max<LayoutUnit>(curr->lineTop(), curr->top());
+            LayoutUnit bottom = min<LayoutUnit>(curr->lineBottom(), curr->top() + curr->height());
+            IntRect rect(pixelSnappedIntRect(layerOffset.x() + curr->x(), layerOffset.y() + top, curr->width(), bottom - top));
+            // It's common for this rect to be entirely contained in our box, so exclude that simple case.
+            if (!rect.isEmpty() && (rects.isEmpty() || !rects[0].contains(rect)))
+                rects.append(rect);
+        }
+    }
+}
+
 RenderBox* RenderBlock::createAnonymousBoxWithSameTypeAs(const RenderObject* parent) const
 {
     if (isAnonymousColumnsBlock())