Remove DOM prefix from plugins IDL interfaces

Source/core/plugins/DOMPlugin.idl

-/*
-    Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
-    Copyright (C) 2008 Apple Inc. All rights reserved.
-
-    This library is free software; you can redistribute it and/or
-    modify it under the terms of the GNU Library General Public
-    License as published by the Free Software Foundation; either
-    version 2 of the License, or (at your option) any later version.
-
-    This library is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-    Library General Public License for more details.
-
-    You should have received a copy of the GNU Library General Public License
-    along with this library; see the file COPYING.LIB.  If not, write to
-    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-    Boston, MA 02110-1301, USA.
-*/
-
-[
-    InterfaceName=Plugin
-] interface DOMPlugin {
-    readonly attribute DOMString name;
-    readonly attribute DOMString filename;
-    readonly attribute DOMString description;
-    readonly attribute unsigned long length;
-    getter DOMMimeType item([Default=Undefined] optional unsigned long index);
-    getter DOMMimeType namedItem([Default=Undefined] optional DOMString name);
-};
-