Reviewed by Gavin Barraclough.

        Look-ahead assertions with back references don’t work as expected
        https://bugs.webkit.org/show_bug.cgi?id=56082

        Changed parentheses assertion processing to temporarily back out the 
        number of known characters after the assertion while processing the 
        assertion.  This was done so that assertions don't fail due to 
        checking the number of required characters as additional to the 
        rest of the express since assertions don't "consume" input.
        Added a byte code to uncheck characters to support the change.

        * yarr/YarrInterpreter.cpp:
        (JSC::Yarr::Interpreter::matchDisjunction):
        (JSC::Yarr::ByteCompiler::uncheckInput):
        (JSC::Yarr::ByteCompiler::emitDisjunction):
        * yarr/YarrInterpreter.h:
        (JSC::Yarr::ByteTerm::UncheckInput):
2011-03-14  Michael Saboff  <msaboff@apple.com>

        Reviewed by Gavin Barraclough.

        Look-ahead assertions with back references don’t work as expected
        https://bugs.webkit.org/show_bug.cgi?id=56082

        New tests to verify the corresponding changes.

        * fast/regex/assertion-expected.txt: Added.
        * fast/regex/assertion.html: Added.
        * fast/regex/script-tests/assertion.js: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@81085 268f45cc-cd09-0410-ab3c-d52691b4dbfc