[turbofan] Drop broken StaticParameterTraits.

The StaticParameterTraits are broken by design, and cause way too much
trouble. The compilers usually pick the wrong specialization (i.e. the
default specialization is picked for Load and Phi even tho there is a
specialization for MachineType), which is not only the reason why GVN is
ineffective and slow, but can also lead to correctness issues in some
rare cases.

Also clean up some minor bugs/inconsistencies on the way.

TEST=cctest,unittests
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/636893002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24437 ce2b1a6d-e550-0410-aec6-3dcde31c8c00