Add tests and extension verifying CHECK and ASSERT.

The new native functions can also be used in blink tests to ensure that V8 asserts are turned on where they should be.

BUG=
R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/105953005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18262 ce2b1a6d-e550-0410-aec6-3dcde31c8c00