Do not send content-type header on the subsequent GET request that occurs as a

result of a POST operation redirection.

Fixes bug for khtml. For kdewebkit, the fix needs to be done upstream and as
such as ticket has been opened there. See http://webkit.org/b/60440.

BUG: 269694
FIXED-IN: 4.6.4

(cherry picked from commit 38eefc85)