[turbofan] Fix the node matchers.

E.g. make sure that Int32Matcher matches only int32 constants, and
Float64Matcher matches only float64 constants.

Also remove the confusing CommonOperatorTraits, which are too easy
to use in a wrong way.

TEST=compiler-unittests,cctest
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/552653003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23768 ce2b1a6d-e550-0410-aec6-3dcde31c8c00