- fix for http://bugzilla.opendarwin.org/show_bug.cgi?id=5461
          Text width measured incorrectly when text-align: justify

WebCore:
        * khtml/rendering/font.h:
        * khtml/rendering/font.cpp:
        (khtml::Font::selectionRectForText): Added.
        * khtml/rendering/render_text.cpp:
        (kthml::InlineTextBox::selectionRect): Use selectionRectForText. This
        works for justified text as well, and avoids intermediate rounding which
        resulted in selection rects narrower than AppKit's.
        (khtml::InlineTextBox::positionForOffset): Use selectionRectForText,
        which works for justified text as well.
        * kwq/KWQFontMetrics.h:
        * kwq/KWQFontMetrics.mm:
        (QFontMetrics::selectionRectForText): Added.
        * kwq/WebCoreTextRenderer.h:

WebKit:
        * WebCoreSupport.subproj/WebTextRenderer.m:
        (-[WebTextRenderer selectionRectForRun:style:geometry:]): Added.
        (CG_drawHighlight): Use new function CG_selectionRect.
        (CG_selectionRect): New function to compute the selection rect.
        Eliminated rounding hackery that was required for keeping the highlight
        rect within the selection rect computed by
        InlineTextBox::selectionRect, since the latter uses this function now.
        The new selection rect is wider and matches AppKit more closely,
        although the right hand side is roundf()ed instead of cielf()ed for
        optimal caret positioning.
        (ATSU_drawHighlight): Use new function ATSU_selectionRect.
        (ATSU_selectionRect): New function to compute the selection rect.
        Much like CG_selectionRect.
LayoutTests:
        * fast/text/justified-text-rect-expected.checksum: Added.
        * fast/text/justified-text-rect-expected.png: Added.
        * fast/text/justified-text-rect-expected.txt: Added.
        * fast/text/justified-text-rect.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@11846 268f45cc-cd09-0410-ab3c-d52691b4dbfc