Reviewed by John

    Reviewed by John

        Removed closestRenderedPosition function from Position class and gave this work
        to VisiblePosition instead. However, in order to make the transfer possible,
        VisiblePosition needed upstream and downstream affinities added to its
        constructors. Also moved the EAffinity enum into its own file. Also moved it
        to the khtml namespace.

        Updated several functions which used closestRenderedPosition to use VisiblePosition
        instead.

        Also deleted Position::equivalentShallowPosition. This was unused.

        * ForwardingHeaders/editing/text_affinity.h: Added.
        * ForwardingHeaders/editing/visible_position.h: Added.
        * WebCore.pbproj/project.pbxproj: Added new files.
        * khtml/editing/selection.cpp:
        (khtml::Selection::validate): Use VisiblePosition instead of closestRenderedPosition.
        * khtml/editing/selection.h:
        * khtml/editing/text_affinity.h: Added.
        * khtml/editing/visible_position.cpp:
        (khtml::VisiblePosition::VisiblePosition):
        (khtml::VisiblePosition::initUpstream): New helper for finding upstream visible position.
        (khtml::VisiblePosition::initDownstream): Was old init function that unconditionally did
        downstream checks for visible position. Renamed to describe this more clearly.
        * khtml/editing/visible_position.h:
        * khtml/editing/visible_units.cpp:
        (khtml::previousWordBoundary): Use VisiblePosition instead of closestRenderedPosition.
        (khtml::nextWordBoundary): Use VisiblePosition instead of closestRenderedPosition.
        * khtml/xml/dom_docimpl.cpp:
        (DocumentImpl::updateSelection): Use VisiblePosition instead of closestRenderedPosition.
        * khtml/xml/dom_position.cpp:
        (DOM::Position::closestRenderedPosition): Removed.
        * khtml/xml/dom_position.h: Removed two functions mentioned above.
        * kwq/KWQKHTMLPart.mm:
        (KWQKHTMLPart::fontForSelection) Use VisiblePosition instead of closestRenderedPosition.:
        * kwq/WebCoreBridge.mm:
        (-[WebCoreBridge setSelectedDOMRange:affinity:]): Use VisiblePosition instead of closestRenderedPosition.
        * layout-tests/editing/deleting/delete-block-merge-contents-012-expected.txt: Updated expected results.
        * layout-tests/editing/deleting/delete-block-merge-contents-017-expected.txt: Ditto.
        * layout-tests/editing/deleting/delete-contiguous-ws-001-expected.txt: Ditto.
        * layout-tests/editing/selection/move-by-character-004-expected.txt: Ditto.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@7691 268f45cc-cd09-0410-ab3c-d52691b4dbfc