Remove TextIterator argumentless constructor
https://bugs.webkit.org/show_bug.cgi?id=113226

Reviewed by Ryosuke Niwa.

The TextIterator argumentless constructors are never used and wouldn't be useful
since you can't specify a range.

No new tests, removing dead code. There should be no behavior change.

* editing/TextIterator.cpp: Remove constructors.
* editing/TextIterator.h:
(TextIterator):
(SimplifiedBackwardsTextIterator):
(CharacterIterator):
(BackwardsCharacterIterator):
(WordAwareIterator):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146796 268f45cc-cd09-0410-ab3c-d52691b4dbfc