Replace Element::isMediaElement() with isHTMLMediaElement

Source/core/html/HTMLSourceElement.cpp

Index: Source/core/html/HTMLSourceElement.cpp
diff --git a/Source/core/html/HTMLSourceElement.cpp b/Source/core/html/HTMLSourceElement.cpp
index 08d4f7cc7621253cd0e37bd768e84b36e26808c7..b1618268c4eb81630dd82be80a15faeef31ea134 100644
--- a/Source/core/html/HTMLSourceElement.cpp
+++ b/Source/core/html/HTMLSourceElement.cpp
@@ -55,8 +55,8 @@ Node::InsertionNotificationRequest HTMLSourceElement::insertedInto(ContainerNode
 {
     HTMLElement::insertedInto(insertionPoint);
     Element* parent = parentElement();
-    if (parent && parent->isMediaElement())
-        toHTMLMediaElement(parentNode())->sourceWasAdded(this);
+    if (isHTMLMediaElement(parent))
+        toHTMLMediaElement(parent)->sourceWasAdded(this);
     return InsertionDone;
 }
 
@@ -65,7 +65,7 @@ void HTMLSourceElement::removedFrom(ContainerNode* removalRoot)
     Element* parent = parentElement();
     if (!parent && removalRoot->isElementNode())
         parent = toElement(removalRoot);
-    if (parent && parent->isMediaElement())
+    if (isHTMLMediaElement(parent))
         toHTMLMediaElement(parent)->sourceWasRemoved(this);
     HTMLElement::removedFrom(removalRoot);
 }