[OpenJDK 2D-Dev] RFR: 8180501: RescaleOp.filter does not document IllegalArgumentException if sizes differ.

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8180501
Webrev: http://cr.openjdk.java.net/~prr/8180501/
RescaleOp has never documented that it throws IAE for different sized 
images,
even though it always has done so ..

A CSR has been filed for this.

https://bugs.openjdk.java.net/browse/JDK-8189826

Please review that also.

-phil