To implement the HttpOnly attribute, the CookieJar needs to know where a
request originated from. Namely, it needs to distinguish between HTTP /
non-HTTP (i.e. JavaScript) requests. When the HttpOnly attribute is set,
requests from JavaScript are to be blocked.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
