Reviewed by Oliver Hunt.

        Bug 21364: Remove the branch in op_ret for OptionalCalleeActivation and OptionalCalleeArguments
        <https://bugs.webkit.org/show_bug.cgi?id=21364>

        Use information from the parser to detect whether an activation is
        needed or 'arguments' is used, and emit explicit instructions to tear
        them off before op_ret. This allows a branch to be removed from op_ret
        and simplifies some other code. This does cause a small change in the
        behaviour of 'f.arguments'; it is no longer live when 'arguments' is not
        mentioned in the lexical scope of the function.

        It should now be easy to remove the OptionaCalleeActivation slot in the
        call frame, but this will be done in a later patch.

        JavaScriptCore:

        * VM/CTI.cpp:
        (JSC::CTI::privateCompileMainPass):
        * VM/CodeBlock.cpp:
        (JSC::CodeBlock::dump):
        * VM/CodeGenerator.cpp:
        (JSC::CodeGenerator::emitReturn):
        * VM/CodeGenerator.h:
        * VM/Machine.cpp:
        (JSC::Machine::unwindCallFrame):
        (JSC::Machine::privateExecute):
        (JSC::Machine::retrieveArguments):
        (JSC::Machine::cti_op_create_arguments):
        (JSC::Machine::cti_op_tear_off_activation):
        (JSC::Machine::cti_op_tear_off_arguments):
        * VM/Machine.h:
        * VM/Opcode.h:
        * kjs/Arguments.cpp:
        (JSC::Arguments::mark):
        * kjs/Arguments.h:
        (JSC::Arguments::isTornOff):
        (JSC::Arguments::Arguments):
        (JSC::Arguments::copyRegisters):
        (JSC::JSActivation::copyRegisters):
        * kjs/JSActivation.cpp:
        (JSC::JSActivation::argumentsGetter):
        * kjs/JSActivation.h:

        LayoutTests:

        * fast/js/function-dot-arguments-expected.txt:
        * fast/js/resources/function-dot-arguments.js:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@37324 268f45cc-cd09-0410-ab3c-d52691b4dbfc