I saw a 3% sloth effect from a huge (100k) history.  This change cut that cost in half.
	I think we still have a marginally measurable cost for our worst practical case.

        Reviewed by rjw

        * History.subproj/WebHistoryPrivate.m:
        (-[WebHistoryPrivate insertEntry:atDateIndex:]):  Comment.
        (-[WebHistoryPrivate removeEntryForURLString:]):  Use removeIdentical
	instead of remove, since we don't need to do all the equals comparisons.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@3031 268f45cc-cd09-0410-ab3c-d52691b4dbfc