[9] Review request for JDK-8054543 Setting a border on a JLayer causes an Exceptions

[Alexander Potochkin]

Hello

Please review the fix the the following RFE:
https://bugs.openjdk.java.net/browse/JDK-8054543
JLayer.setBorder() method is implemented to constantly throw an 
IllegalArgumentException for every parameter except null. It breaks some 
of the third party libraries which set borders for a component they are 
receiving.

The proposed API change provides the required API for JDK9
http://cr.openjdk.java.net/~alexp/8054543/webrev.00/

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

Thanks
alexp