Reviewed by Beth.

        Some clean up of AccessibilityObject:
        - Use existing isImage() in more places.
        - Use existing isTextControl() in more places.
        - Added isRenderImage(). Check this before casting to RenderImage,
          since other, non-RenderImage derived RenderObjects (e.g.
          RenderListMarker) can return true for isImage().
        - Fix two copy/paste errors with improper semicolons.

        * page/AccessibilityObject.cpp:
        (WebCore::AccessibilityObject::isImageButton): Use isImage().
        (WebCore::AccessibilityObject::isRenderImage): Added.
        (WebCore::AccessibilityObject::isAnchor): Use isImage().
        (WebCore::AccessibilityObject::isAttachment): Same.
        (WebCore::AccessibilityObject::accessibilityDescription): Same.
        (WebCore::AccessibilityObject::accessibilityIsIgnored): Use
        isRenderImage() instead of isImage().
        (WebCore::AccessibilityObject::url): Use isImage().
        (WebCore::AccessibilityObject::textControl): Remove improper semicolon, 
        and use isTextControl().
        (WebCore::AccessibilityObject::textMarkerForIndex): Same.
        (WebCore::AccessibilityObject::indexForTextMarker): Use isTextControl().
        (WebCore::AccessibilityObject::doAXRangeForLine): Same.
        (WebCore::AccessibilityObject::doAXRangeForIndex): Same
        (WebCore::AccessibilityObject::doAXStringForRange): Same.
        (WebCore::AccessibilityObject::roleValue):  Use isImage().
        (WebCore::AccessibilityObject::addChildren): Use isRenderImage().
        * page/AccessibilityObject.h:




git-svn-id: http://svn.webkit.org/repository/webkit/trunk@31643 268f45cc-cd09-0410-ab3c-d52691b4dbfc