Reviewed by Darin.

        - Fix http://bugzilla.opendarwin.org/show_bug.cgi?id=9358
          REGRESSION: Assertion failure in HTMLInputElement::setValueFromRenderer
          (value == constrainValue(value)) when deleting all text

        Test: editing/deleting/delete-all-text-in-text-field-assertion.html

        Bug 9661 filed to fix the follow-up issue:
        http://bugzilla.opendarwin.org/show_bug.cgi?id=9661
        textContent returns "\n" for a <br> even if it is collapsed

        * html/HTMLInputElement.cpp:
        (WebCore::HTMLInputElement::setValueFromRenderer): Work around "\n" value
        when all characters are deleted from a text field.

LayoutTests:

        Reviewed by Darin.

        - Test for http://bugzilla.opendarwin.org/show_bug.cgi?id=9358
          REGRESSION: Assertion failure in HTMLInputElement::setValueFromRenderer
          (value == constrainValue(value)) when deleting all text

        * editing/deleting/delete-all-text-in-text-field-assertion-expected.txt: Added.
        * editing/deleting/delete-all-text-in-text-field-assertion.html: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@15111 268f45cc-cd09-0410-ab3c-d52691b4dbfc