Enable "unreachable code" warning for MSVC.

Enable "unreachable code" warning for MSVC.

BUG=346399
TEST=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272687

[scottmg, 2014-05-22 23:39:06]

lgtm

https://codereview.chromium.org/260903003/diff/20001/build/common.gypi
File build/common.gypi (right):

https://codereview.chromium.org/260903003/diff/20001/build/common.gypi#newcod...
build/common.gypi:4920: # to VS2013 Update 2.
Please add crbug/what 4702 is here.

[Peter Kasting, 2014-05-23 17:51:16]

https://codereview.chromium.org/260903003/diff/20001/build/common.gypi
File build/common.gypi (right):

https://codereview.chromium.org/260903003/diff/20001/build/common.gypi#newcod...
build/common.gypi:4920: # to VS2013 Update 2.
On 2014/05/22 23:39:06, scottmg wrote:
> Please add crbug/what 4702 is here.

Done.

[Peter Kasting, 2014-05-23 17:51:20]

The CQ bit was checked by pkasting@chromium.org

[commit-bot: I haz the power, 2014-05-23 17:52:46]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/pkasting@chromium.org/260903003/40001

[commit-bot: I haz the power, 2014-05-23 22:36:18]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-05-24 02:35:30]

Change committed as 272687