Reviewed by Kent Tamura.

        Remove calls to deprecatedEditingOffset in SelectionController and VisibleSelection
        https://bugs.webkit.org/show_bug.cgi?id=54937

        * editing/SelectionController.cpp:
        (WebCore::SelectionController::setSelection): Calls anchorNode() instead of deprecatedNode() to obtain
        the document. Also restrained the lifetime of document variable.
        (WebCore::removingNodeRemovesPosition): Compare the node with anchorNode() instead of deprecatedNode()
        to determine whether or not position becomes null after removing a node.
        (WebCore::SelectionController::directionOfEnclosingBlock): The enclosing block is always a container
        so call containerNode() instead of deprecatedNode().
        (WebCore::SelectionController::debugRenderer): Call containerNode() and computeOffsetInContainer()
        instead of deprecatedNode() and deprecatedEditingOffset() respectively.
        (WebCore::SelectionController::isInPasswordField): Look for the shadow root from containerNode()
        instead of deprecatedNode to determine whether or not selection inside a password field. Also assert
        that the specified position is not before or after the shadow root as it violates our assumption.
        * editing/VisibleSelection.cpp:
        (WebCore::makeSearchRange): Call containerNode() and offsetInContainerNode() instead of deprecatedNode()
        and deprecatedEditingOffset() respectively because start is always parent anchored and therefore
        guaranteed to be an offset inside an anchor node.
        (WebCore::VisibleSelection::adjustSelectionToAvoidCrossingEditingBoundaries): Call containerNode()
        instead of deprecatedNode() to look for the lowest editable ancestor because position before or after
        an editable element isn't editable.
        * page/DOMSelection.cpp: Call containerNode() and offsetInContainerNode() instead of deprecatedNode()
        and deprecatedEditingOffset() respectively in the following functions because they are exposed to
        DOM, which doesn't have before/after concept.
        (WebCore::DOMSelection::anchorNode):
        (WebCore::DOMSelection::anchorOffset):
        (WebCore::DOMSelection::focusNode):
        (WebCore::DOMSelection::focusOffset):
        (WebCore::DOMSelection::baseNode):
        (WebCore::DOMSelection::baseOffset):
        (WebCore::DOMSelection::extentNode):
        (WebCore::DOMSelection::extentOffset):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@80604 268f45cc-cd09-0410-ab3c-d52691b4dbfc