Remove deprecated and unused run_and_throw_if_fail from webkitpy

This function was used by build-webkit according to it's comment.
Currently it is used by FlakyTests and some unit tests but it can
be replaced with run_command

Review URL: https://codereview.chromium.org/663023008

git-svn-id: svn://svn.chromium.org/blink/trunk@184157 bbb929c8-8fbe-4397-9dbb-9b2b20218538