Reviewed by Adam Barth.

        Add test for XSLT NULL crash:
        https://bugs.webkit.org/show_bug.cgi?id=36804

        * LayoutTests/fast/xsl/xslt-bad-import-uri.html: added
        * LayoutTests/fast/xsl/xslt-bad-import-uri-expected.txt: added
        * LayoutTests/fast/xsl/resources/xslt-bad-import-uri.xml: added
        * LayoutTests/fast/xsl/resources/xslt-bad-import-uri.xsl: added
2010-04-01  Chris Evans  <cevans@chromium.org>

        Reviewed by Adam Barth.

        Fix a NULL pointer crash if @import fails to load a stylesheet.

        https://bugs.webkit.org/show_bug.cgi?id=36804

        Test: fast/xsl/xslt-bad-import-uri.html

        * xml/XSLStyleSheetLibxslt.cpp:
        (WebCore::XSLStyleSheet::parseString):
          Handle an empty string gracefully. An empty string has a NULL
          buffer, which we pass in to xmlCreateMemoryParserCtxt(). It returns
          NULL if it is passed a NULL buffer.
          In the top-level XSL case, the current code does not crash "by luck"
          because the other APIs used can handle a NULL argument. In the
          @import case, additional code runs which will deference the NULL.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@56956 268f45cc-cd09-0410-ab3c-d52691b4dbfc