Revert of Disable the image notification property on MacOS

Revert of Disable the image notification property on MacOS (patchset #3 id:40001 of https://codereview.chromium.org/2803303002/ )

Reason for revert:
This broke a bunch of webkit tests.

https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Mac10.10/builds/32377

I think you need to update the test results when you remove the feature.


Original issue's description:
> Disable the image notification property on MacOS
> 
> This is in preparation for the launch of MacOSX native notifications
> where the property is not supported.
> 
> Intent to remove https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/IKGgHJOVMYE
> 
> BUG=571056
> 
> Review-Url: https://codereview.chromium.org/2803303002
> Cr-Commit-Position: refs/heads/master@{#463050}
> Committed: https://chromium.googlesource.com/chromium/src/+/ae910dd7ccf483d4c3b57cefafda32f36baf7ab9

TBR=peter@chromium.org,avi@chromium.org,miguelg@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=571056

[haraken, 2017-04-10 04:51:35]

The CQ bit was checked by haraken@chromium.org

[haraken, 2017-04-10 04:51:35]

Created Revert of Disable the image notification property on MacOS

[commit-bot: I haz the power, 2017-04-10 04:51:50]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-10 04:53:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-10 04:53:41]

Try jobs failed on following builders:
  ios-device on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device/builds...)
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  mac_chromium_compile_dbg_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[Mike West, 2017-04-10 09:35:46]

mkwst@chromium.org changed reviewers:
+ mkwst@chromium.org

[Mike West, 2017-04-10 09:35:47]

Manually reverting in https://codereview.chromium.org/2806233003.