Make AttachBehavior a required argument.

Source/core/html/track/TextTrackCue.cpp

Index: Source/core/html/track/TextTrackCue.cpp
diff --git a/Source/core/html/track/TextTrackCue.cpp b/Source/core/html/track/TextTrackCue.cpp
index 7c42af0473b612cd59be658ab932732969a6de33..3ffac8c5fb4b0eee5ec396571e3b36b6d2f7c9ca 100644
--- a/Source/core/html/track/TextTrackCue.cpp
+++ b/Source/core/html/track/TextTrackCue.cpp
@@ -506,7 +506,7 @@ void TextTrackCue::copyWebVTTNodeToDOMTree(ContainerNode* webVTTNode, ContainerN
             clonedNode = toWebVTTElement(node)->createEquivalentHTMLElement(ownerDocument());
         else
             clonedNode = node->cloneNode(false);
-        parent->appendChild(clonedNode, ASSERT_NO_EXCEPTION);
+        parent->appendChild(clonedNode, ASSERT_NO_EXCEPTION, DeprecatedAttachNow);
         if (node->isContainerNode())
             copyWebVTTNodeToDOMTree(toContainerNode(node), toContainerNode(clonedNode.get()));
     }
@@ -780,7 +780,7 @@ void TextTrackCue::updateDisplayTree(double movieTime)
     // Update the two sets containing past and future WebVTT objects.
     RefPtr<DocumentFragment> referenceTree = createCueRenderingTree();
     markFutureAndPastNodes(referenceTree.get(), startTime(), movieTime);
-    m_cueBackgroundBox->appendChild(referenceTree);
+    m_cueBackgroundBox->appendChild(referenceTree, ASSERT_NO_EXCEPTION, DeprecatedAttachNow);
 }
 
 PassRefPtr<TextTrackCueBox> TextTrackCue::getDisplayTree(const IntSize& videoSize)