[CSS Regions] Add new regionOversetChange event

Source/core/rendering/RenderNamedFlowThread.cpp

Index: Source/core/rendering/RenderNamedFlowThread.cpp
diff --git a/Source/core/rendering/RenderNamedFlowThread.cpp b/Source/core/rendering/RenderNamedFlowThread.cpp
index f83f46c78a403812d6227a5676ff8ffd2cbd0b6e..f9b34f54d7b876398c1a6570d30932ef32687ac2 100644
--- a/Source/core/rendering/RenderNamedFlowThread.cpp
+++ b/Source/core/rendering/RenderNamedFlowThread.cpp
@@ -55,6 +55,7 @@ RenderNamedFlowThread* RenderNamedFlowThread::createAnonymous(Document* document
 RenderNamedFlowThread::RenderNamedFlowThread(PassRefPtr<NamedFlow> namedFlow)
     : m_namedFlow(namedFlow)
     , m_regionLayoutUpdateEventTimer(this, &RenderNamedFlowThread::regionLayoutUpdateEventTimerFired)
+    , m_regionOversetChangeEventTimer(this, &RenderNamedFlowThread::regionOversetChangeEventTimerFired)
 {
 }
 
@@ -425,6 +426,14 @@ void RenderNamedFlowThread::dispatchRegionLayoutUpdateEvent()
         m_regionLayoutUpdateEventTimer.startOneShot(0);
 }
 
+void RenderNamedFlowThread::dispatchRegionOversetChangeEvent()
+{
+    RenderFlowThread::dispatchRegionOversetChangeEvent();
+
+    if (!m_regionOversetChangeEventTimer.isActive() && m_namedFlow->hasEventListeners())
+        m_regionOversetChangeEventTimer.startOneShot(0);
+}
+
 void RenderNamedFlowThread::regionLayoutUpdateEventTimerFired(Timer<RenderNamedFlowThread>*)
 {
     ASSERT(m_namedFlow);
@@ -432,6 +441,13 @@ void RenderNamedFlowThread::regionLayoutUpdateEventTimerFired(Timer<RenderNamedF
     m_namedFlow->dispatchRegionLayoutUpdateEvent();
 }
 
+void RenderNamedFlowThread::regionOversetChangeEventTimerFired(Timer<RenderNamedFlowThread>*)
+{
+    ASSERT(m_namedFlow);
+
+    m_namedFlow->dispatchRegionOversetChangeEvent();
+}
+
 void RenderNamedFlowThread::setMarkForDestruction()
 {
     if (m_namedFlow->flowState() == NamedFlow::FlowStateNull)