[10] Review request: 8178521 Severe performance drop for path rendering

[Jim Graham]

Review history already in JBS: https://bugs.openjdk.java.net/browse/JDK-8178521
final webrev: http://cr.openjdk.java.net/~flar/JDK-8178521/webrev.02/

This should be considered for a backport to 9 as well...

                        ...jim