[10] Review request: 8188314: Fix typos in FX API docs

[Kevin Rushforth]

I'm sending this review on behalf of Jon Gibbons who provided the fix 
for these javadoc errors:

https://bugs.openjdk.java.net/browse/JDK-8188314
http://cr.openjdk.java.net/~jjg/8188314/webrev.00/
-- Kevin