https://bugs.webkit.org/show_bug.cgi?id=109463.

Reviewed by Ryosuke Niwa.
        
This patch adds #if ENABLE(DELETION_UI) in every spot where
DeleteButtonController is used. This class is now only instantiated
if the feature is enabled. I've also done some cleanup in the
DeleteButtonController class, removing unused methods and making
private some methods only used internally to the class.
Both DeleteButtonController and DeleteButton classes are now excluded
from the compilation if the feature is not enabled.

No new tests, no change of functionality.

* dom/ContainerNode.cpp:
(WebCore::ContainerNode::cloneChildNodes):
* editing/CompositeEditCommand.cpp:
(WebCore::EditCommandComposition::unapply):
(WebCore::EditCommandComposition::reapply):
(WebCore::CompositeEditCommand::apply):
* editing/DeleteButton.cpp:
* editing/DeleteButtonController.cpp:
* editing/DeleteButtonController.h: Some cleanup.
(WebCore::DeleteButtonController::enabled): Made private.
* editing/EditCommand.cpp:
(WebCore::EditCommand::EditCommand):
* editing/Editor.cpp:
(WebCore::Editor::notifyComponentsOnChangedSelection):
(WebCore::Editor::Editor):
(WebCore::Editor::rangeForPoint):
(WebCore::Editor::deviceScaleFactorChanged):
* editing/Editor.h:
* editing/htmlediting.cpp: avoidIntersectionWithNode is
used only if the feature is enabled.
* editing/htmlediting.h:
* editing/markup.cpp:
(WebCore::createMarkup):
(WebCore::createFragmentFromNodes):
* rendering/RenderTable.cpp: Removed unnecessary include
fo DeleteButtonController.h

Source/WTF: Add ENABLE_DELETION_UI to control the use of the deletion UI.
https://bugs.webkit.org/show_bug.cgi?id=109463.
        
ENABLE_DELETION_UI is set to 1 by default for
all ports. It is explicitly enabled for MAC and disabled for iOS.

Reviewed by Ryosuke Niwa.

* wtf/Platform.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142533 268f45cc-cd09-0410-ab3c-d52691b4dbfc