Merge IR classes for different bitwise operations AND, OR and XOR into one class.

Merge IR classes for different bitwise operations AND, OR and XOR into one class.

Since we already have only one LIR class, it does not make much sense to separate
them at the HIR level.
Review URL: http://codereview.chromium.org/8426005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9846 ce2b1a6d-e550-0410-aec6-3dcde31c8c00