Make sure the dominant line direction is properly set for RTL runs so that spaces...

	Make sure the dominant line direction is properly set for RTL runs so that spaces will reverse.

	Change xHeight to measure the ascent of the x glyph, since the xHeight metrics appear to be
	totally bogus in both CG and AppKit.

        Reviewed by darin

        * WebCoreSupport.subproj/WebTextRenderer.m:
        (-[WebTextRenderer xHeight]):
        (-[WebTextRenderer _createATSUTextLayoutForRun:style:]):
        (-[WebTextRenderer _trapezoidForRun:style:atPoint:]):
        (-[WebTextRenderer _ATSU_drawHighlightForRun:style:geometry:]):
        (-[WebTextRenderer _ATSU_drawRun:style:geometry:]):
        (-[WebTextRenderer _ATSU_pointToOffset:style:position:reversed:includePartialGlyphs:]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@7940 268f45cc-cd09-0410-ab3c-d52691b4dbfc