Support slotchange event

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp

Index: third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
diff --git a/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp b/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
index 76797f1bd010a02dce6a3792e3d6d5a84de32faa..fac6fa65bb8d5075371431f36b548760d569fa30 100644
--- a/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
+++ b/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
@@ -344,13 +344,20 @@ const HeapVector<Member<HTMLSlotElement>>& ShadowRoot::descendantSlots()
     return m_shadowRootRareData->descendantSlots();
 }
 
-void ShadowRoot::distributeV1()
+void ShadowRoot::assignV1()
 {
     if (!m_slotAssignment)
         m_slotAssignment = SlotAssignment::create();
     m_slotAssignment->resolveAssignment(*this);
 }
 
+void ShadowRoot::distributeV1()
+{
+    if (!m_slotAssignment)
+        m_slotAssignment = SlotAssignment::create();
+    m_slotAssignment->resolveDistribution(*this);
+}
+
 DEFINE_TRACE(ShadowRoot)
 {
     visitor->trace(m_prev);