Revert of Fix the mechanism by which Blink determines OSX version number.

Revert of Fix the mechanism by which Blink determines OSX version number. (patchset #4 id:60001 of https://codereview.chromium.org/1301693002/ )

Reason for revert:
VersionUtilMac.AppKitVersions fails on OSX 10.6 and 10.7.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=blink_platform_unittests&showExpectations=true&tests=VersionUtilMac.AppKitVersions


Original issue's description:
> Fix the mechanism by which Blink determines OSX version number.
> 
> Previously, Blink was checking NSAppKitVersionNumber against a compile time
> constant. This mechanism doesn't work (see the bug for more details). This CL
> converts the logic to use the same mechanism that Chromium uses.
> 
> BUG=521034
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200708

TBR=thakis@chromium.org,erikchen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=521034
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200711

[tkent, 2015-08-18 07:39:53]

Created Revert of Fix the mechanism by which Blink determines OSX version
number.

[commit-bot: I haz the power, 2015-08-18 07:39:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1286233004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1286233004/1

[commit-bot: I haz the power, 2015-08-18 07:40:21]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200711