chromium: Update to latest beta and dev channels
Overview of the updated versions:
beta: 50.0.2661.49 -> 51.0.2704.47
dev: 51.0.2693.2 -> 52.0.2729.3
It has been a while since we had a major Chromium update that compiled
and worked without troubles, but version 52 builds and the VM tests are
successful as well:
https://headcounter.org/hydra/eval/320335
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
(cherry picked from commit ad2c8d3510eaec68861a610574b09aca45b9cad3)
Reason: 50.0.2661.102 fixes a bunch of security vulnerabilities and
we want to have them fixed in beta/dev as well.
