8u40 review request: RT-39275 bad bounds leading to repaint issues in Ensemble8/TextFlow

[Jim Graham]

webrev: http://cr.openjdk.java.net/~flar/RT-39275/webrev.00/
Jira: https://javafx-jira.kenai.com/browse/RT-39275
Long explanations about the rework of the original fix for RT-36130 are 
in the Jira comments...

                        ...jim