Fixed <rdar://problem/3757712> REGRESSION (Mail): WebCore does not allow Devanagari...

	Fixed <rdar://problem/3757712> REGRESSION (Mail): WebCore does not allow Devanagari ligature input

	For now we are using ICU UBreakIterator to determine grapheme boundaries for
	cursor and deletion.  This does not match what Cocoa does exactly, but does match
	what Carbon does.  The areas are difference are obscure, but, according to
	Deborah Goldsmith, using the UBreakIterator is the reasonable approach.

        Reviewed by Ken.

        * khtml/rendering/render_text.cpp:
        (RenderText::previousOffset):
        (RenderText::nextOffset):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8452 268f45cc-cd09-0410-ab3c-d52691b4dbfc