Remove FrameLoader::m_startingClientRedirect and pass it around instead.

Also, switch it to an enum instead of a bool for readability.

BUG=none

Review URL: https://codereview.chromium.org/56403002

git-svn-id: svn://svn.chromium.org/blink/trunk@161199 bbb929c8-8fbe-4397-9dbb-9b2b20218538