review request RT-28691: Region corner radii scaling issues when radii > 2*width,height

[Jim Graham]

Hi David and Felipe,

Please review my proposed fix for: 
https://javafx-jira.kenai.com/browse/RT-28691

The webrev pointer, and a question, are in my recent comment there.

This makes every instance of corner radii handling I could find in 
Region and NGRegion internally consistent, enforced by pre-filtering the 
data through a single method in Region.

I am curious to hear from David about the interpretation I've made of 
various anomalous cases of corner radii, and Felipe from general 
graphics correctness of my calculations.  I mention a specific question 
I had while developing the fix in the Jira comment with the webrev.

I tested it with Ensemble8 and the test cases in the report.  I haven't 
written a specific test case that combines inset+percentage overflow 
until I hear back from David (or anyone) about what the correct 
interpretation is for that case...

			...jim