FTL fails the new equals-masquerader strictEqualConstant test
https://bugs.webkit.org/show_bug.cgi?id=129996

Reviewed by Mark Lam.
        
It turns out that the FTL was trying to do the masquerading stuff for ===null. But
that's wrong since none of the other engines do it. The DFG even had an ancient
FIXME about doing it - but that doesn't make sense since the LLInt and baseline JIT
don't do it and JSValue::strictEqual() doesn't do it.
        
Remove the FIXME and remove the extra checks in the FTL.
        
This is a glorious patch: nothing but red and it fixes a test failure.

* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileStrictEqForConstant):
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::LowerDFGToLLVM::compileCompareStrictEqConstant):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@165358 268f45cc-cd09-0410-ab3c-d52691b4dbfc