[9] Review request for JDK-8041982 Use of animated icon in JLayer causes CPU spin

[Alexander Potochkin]

Hello

Please review the fix the the following RFE:
https://bugs.openjdk.java.net/browse/JDK-8041982
JLayer/LayerUI classes don't currently allow to override the 
imageUpate() method
to control the specific cases involved animated gif images.

The proposed API change provides the required API for JDK9
http://cr.openjdk.java.net/~alexp/8041982/webrev.00/

The request to the public API change will be filed after the technical 
review

Thanks
alexp