Rework compositor touch hit testing

Source/core/rendering/RenderLayerModelObject.cpp

Index: Source/core/rendering/RenderLayerModelObject.cpp
diff --git a/Source/core/rendering/RenderLayerModelObject.cpp b/Source/core/rendering/RenderLayerModelObject.cpp
index 6c11f67c8c8a813390bee8056206c73c88807fec..041be48338ebf237dc6387e8880d869342ee6b03 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -26,6 +26,7 @@
 #include "core/rendering/RenderLayerModelObject.h"
 
 #include "core/rendering/RenderLayer.h"
+#include "core/rendering/RenderLayerBacking.h"
 #include "core/rendering/RenderView.h"
 
 using namespace std;
@@ -189,5 +190,18 @@ void RenderLayerModelObject::reportMemoryUsage(MemoryObjectInfo* memoryObjectInf
     info.addWeakPointer(m_layer);
 }
 
+void RenderLayerModelObject::addLayerHitTestRects(LayerHitTestRects& rects, const RenderLayer* currentCompositedLayer, const LayoutPoint& layerOffset) const
+{
+    // If we have a self painting layer then our current layer/offset is irrelevant.
+    // TODO: I don't think this is quite the right approach in the general case.
+    // Rather than update the offset, we probably need to map quads from one layer space
+    // to another, taking into account transforms (eg. scale) and clips (eg. overflow).
+    LayoutPoint adjustedLayerOffset = layerOffset;
+    if (hasSelfPaintingLayer())
+        enclosingCompositedLayerAndOffset(&currentCompositedLayer, adjustedLayerOffset);
+
+    RenderObject::addLayerHitTestRects(rects, currentCompositedLayer, adjustedLayerOffset);
+}
+
 } // namespace WebCore