Just check/use window object under browserify.
Just check/use window object under browserify.

See: https://github.com/substack/browser-pack/issues/25#issuecomment-31278911

power-assert-js/empower,jamestalmage/empower-assert,jamestalmage/empower-assert,twada/power-assert-runtime,power-assert-js/empower,twada/empower-core,twada/empower-core