Fix master zero-value build property passing.

Fix master zero-value build property passing.

BUG=chromium:516091
TEST=local
  - Started master locally, triggered with build number of 0, confirmed
    that JSON value is now 0 instead of "".

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=296197

[dnj (Google), 2015-08-01 01:31:48]

dnj@google.com changed reviewers:
+ dnj@google.com, hinoka@chromium.org, luqui@chromium.org

[dnj (Google), 2015-08-01 01:31:48]

PTAL

[hinoka, 2015-08-03 11:37:29]

lgtm, presumably we don't render anything that actually wants to be "0"?

[dnj (Google), 2015-08-03 16:01:15]

On 2015/08/03 11:37:29, hinoka wrote:
> lgtm, presumably we don't render anything that actually wants to be "0"?

The first builds of new builders use "0" as the build number, which is where I
hit this.

[dnj (Google), 2015-08-03 16:25:54]

The CQ bit was checked by dnj@google.com

[commit-bot: I haz the power, 2015-08-03 16:26:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1254003005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1254003005/1

[commit-bot: I haz the power, 2015-08-03 16:29:32]

Committed patchset #1 (id:1) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=296197