Reviewed by Sam Weinig.

* dom/Clipboard.cpp:
(WebCore::Clipboard::Clipboard): Move the ClipboardType argument to go after the pasteboard.
Initialize strings more efficiently. Put drag-specific data members inside an if statement.
Replace m_clipboardType with m_forDrag.
(WebCore::Clipboard::createForCopyAndPaste): Moved function up to be close to constructor.
Removed explicit clipboard type since constructor now defaults to copy and paste style.
(WebCore::Clipboard::setAccessPolicy): Tweaked comment.
(WebCore::Clipboard::getData): Put drag-specific code inside #if ENABLE(DRAG_SUPPORT).
(WebCore::Clipboard::setData): Ditto.
(WebCore::Clipboard::files): Ditto.
(WebCore::Clipboard::dropEffect): Added trivial non-drag versions of these functions to
be used when !ENABLE(DRAG_SUPPORT).
(WebCore::Clipboard::setDropEffect): Ditto.
(WebCore::Clipboard::effectAllowed): Ditto.
(WebCore::Clipboard::setEffectAllowed): Ditto.
(WebCore::Clipboard::createForDragAndDrop): Renamed Clipboard::create that takes DragData
to this, and kep the overload that does not as well. Made the DragData argument a const&.
(WebCore::Clipboard::canSetDragImage): Moved down here since it is drag-specific.
(WebCore::Clipboard::updateDragImage): Use m_shouldUpdateDragImage directly insted of
calling a dragStarted function.
(WebCore::dragOpFromIEOp): Moved this function down here to the drag-specific section.
(WebCore::IEOpFromDragOp): Ditto.
(WebCore::Clipboard::sourceOperation): Ditto.
(WebCore::Clipboard::destinationOperation): Ditto.
(WebCore::Clipboard::setSourceOperation): Ditto.
(WebCore::Clipboard::setDestinationOperation): Ditto.

* dom/Clipboard.h: Removed unneeded include of "Node.h" and added and removed forward
class declarations as required. Removed non-helpful comment. Made ClipboardType a private
implementation detail. Moved functions that are not part of the DOM API down to a separate
section lower down in the class, and sorted the functions to match the order they appear
in the IDL file. Removed isForCopyAndPaste and isForDragAndDrop. Changed dropEffect and
effectAllowed to not be inlined. Moved the long comment before canSetDragImage into the
implementation since it's an implementation detail. Since this class is no longer polymorphic,
use only private, not protected. Make m_dragImageElement an Element, not a Node.

* dom/Clipboard.idl: Removed flags to tell bindings how to deal with null strings, since
these string properties can never return null strings anyway.

* page/DragController.cpp:
(WebCore::DragController::dragExited): Updated to call the new createForDragAndDrop function.
(WebCore::DragController::performDrag): Ditto.
(WebCore::DragController::tryDHTMLDrag): Ditto.

* platform/mac/ClipboardMac.mm: Added now-needed include of Element.h since Clipboard.h no
longer includes it.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154260 268f45cc-cd09-0410-ab3c-d52691b4dbfc