Add isHTMLPlugInElement() helpers for consistency with other HTML elements

Source/core/rendering/RenderEmbeddedObject.cpp

Index: Source/core/rendering/RenderEmbeddedObject.cpp
diff --git a/Source/core/rendering/RenderEmbeddedObject.cpp b/Source/core/rendering/RenderEmbeddedObject.cpp
index ff571188b5a3c5f095e7928fcb190ef81a4e7c78..2db078f10ccd94a401fc938dd3728b7e6edb6a9e 100644
--- a/Source/core/rendering/RenderEmbeddedObject.cpp
+++ b/Source/core/rendering/RenderEmbeddedObject.cpp
@@ -28,6 +28,7 @@
 #include "HTMLNames.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLIFrameElement.h"
+#include "core/html/HTMLPlugInElement.h"
 #include "core/page/Page.h"
 #include "core/frame/Settings.h"
 #include "core/plugins/PluginView.h"
@@ -109,7 +110,7 @@ bool RenderEmbeddedObject::showsUnavailablePluginIndicator() const
 void RenderEmbeddedObject::paintContents(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     Element* element = toElement(node());
-    if (!element || !element->isPluginElement())
+    if (!isHTMLPlugInElement(element))
         return;
 
     RenderPart::paintContents(paintInfo, paintOffset);