chromium: Update all channels to latest versions.

This brings in Chromium 27 as the new stable version.

Specific versions of the updated channels:

stable: 26.0.1410.63 -> 27.0.1453.93 (builds fine, tested)
beta:   27.0.1453.81 -> 28.0.1500.20 (builds fine, tested)
dev:    28.0.1500.11 -> 29.0.1516.3  (builds fine, tested)

We now can finally drop the following patches:

 * glibc-2.16-use-siginfo_t.patch
 * pulseaudio_array_bounds.patch

These were for version 26 only and thus are no longer needed.

In addition, we no longer have to use the pre/post attributes, as there is just
_one_ place that uses version specific stuff (path to webcore.gyp).

Signed-off-by: aszlig <aszlig@redmoonstudios.org>