Add JSBuiltinReducer for inlining well-known builtins.

R=titzer@chromium.org
TEST=cctest/test-js-typed-lowering/BuiltinMathImul

Review URL: https://codereview.chromium.org/584573003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24095 ce2b1a6d-e550-0410-aec6-3dcde31c8c00