[CSS Regions] Add new regionOversetChange event

Source/core/dom/NamedFlow.cpp

Index: Source/core/dom/NamedFlow.cpp
diff --git a/Source/core/dom/NamedFlow.cpp b/Source/core/dom/NamedFlow.cpp
index a5b579526050c4448f4164da017e55b898496eae..00519a12aa13ead3270d508c52af3ef58019df5c 100644
--- a/Source/core/dom/NamedFlow.cpp
+++ b/Source/core/dom/NamedFlow.cpp
@@ -103,7 +103,7 @@ int NamedFlow::firstEmptyRegionIndex() const
     RenderRegionList::const_iterator iter = regionList.begin();
     for (int index = 0; iter != regionList.end(); ++index, ++iter) {
         const RenderRegion* renderRegion = *iter;
-        if (renderRegion->regionState() == RenderRegion::RegionEmpty)
+        if (renderRegion->regionOversetState() == RegionEmpty)
             return index;
     }
     return -1;
@@ -217,6 +217,19 @@ void NamedFlow::dispatchRegionLayoutUpdateEvent()
     dispatchEvent(event);
 }
 
+void NamedFlow::dispatchRegionOversetChangeEvent()
+{
+    ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());
+
+    // If the flow is in the "NULL" state the event should not be dispatched any more.
+    if (flowState() == FlowStateNull)
+        return;
+
+    RefPtr<Event> event = UIEvent::create(eventNames().webkitregionoversetchangeEvent, false, false, m_flowManager->document()->defaultView(), 0);
+
+    dispatchEvent(event);
+}
+
 const AtomicString& NamedFlow::interfaceName() const
 {
     return eventNames().interfaceForNamedFlow;