[8u/9] review request for 8139210: JavaFX rendering glitch when rendering many Paths using HW pipeline

[Jim Graham]

I've created 2 versions of the fix for this bug.  One is low source 
impact but maintains the current convoluted role of the VertexBuffer 
class in the code base and makes it slightly more murky.  The second fix 
touches a bunch of files, but it cleans up the use of the VB class 
throughout the code base.

JBS: https://bugs.openjdk.java.net/browse/JDK-8139210

webrev for simple fix (8u & 9): 
http://cr.openjdk.java.net/~flar/JDK-8139210/webrev.00/

webrev for bigger fix (8u): 
http://cr.openjdk.java.net/~flar/JDK-8139210/webrev.alt8u.00/
webrev for bigger fix (9): 
http://cr.openjdk.java.net/~flar/JDK-8139210/webrev.alt9.00/
(the 2 webrevs differ *only* in the location of the TestGraphics.java file)

We should consider this for both 8u and 9.  I recommend going with the 
more complete fix for 9, but which is more appropriate for 8u?

			...jim