When DRT crashes, record stderr and restart DRT

    When DRT crashes, record stderr and restart DRT

        This prevents a DRT crash from causing the next few hundred tests to
        "fail" because DRT is no longer running.

        I also changed the terminology that run-webkit-tests uses in its
        output a bit, so that crashing tests are referred to as "crashes"
        instead of "failures".

        Reviewed by Mark.

        * Scripts/run-webkit-tests: Detect a crash and record it as a tool
        failure.
        (sub openDumpTool): Use open3 so that we can access stderr.
        (sub dumpToolCrashed): Added.
        (sub printFailureMessageForTest): Added.
        (sub htmlForExpectedAndActualResults): Added.
        (sub deleteExpectedAndActualResults): Added.
        (sub recordActualResultsAndDiff): Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@24816 268f45cc-cd09-0410-ab3c-d52691b4dbfc