MFH: r404690

www/firefox: update to 43.0.3

Mainly for YouTube with FFMPEG=off. [1]

Changes: https://hg.mozilla.org/releases/mozilla-release/rev/7f685bdc616a [1]
PR: 205652
Submitted by: Christoph Moench-Tegeder <cmt@burggraben.net>
Security: 10f7bc76-0335-4a88-b391-0b05b3a8ce1c (linux-only)
Approved by: ports-secteam (miwi)