Please Review javadoc warning fixes to java.lang.invoke

[roger riggs]

Please review a couple of issues with javadoc in java.lang.invoke to 
cleanup javadoc warnings.

https://bugs.openjdk.java.net/browse/JDK-8026183
https://bugs.openjdk.java.net/browse/JDK-8015808
Webrev:
   http://cr.openjdk.java.net/~rriggs/webrev-invoke-javadoc-8026183/

Thanks, Roger