[8u] request for review: 8068489: remove unnecessary complexity in Flow and Bits, after JDK-8064857

[Maurizio Cimadamore]

Hi,
Please review the backport of bug:

JDK-8133659: Compiler fails to NullPointerException when calling super 
with Object<>()

JDK9 bug: https://bugs.openjdk.java.net/browse/JDK-8065986
backport: https://bugs.openjdk.java.net/browse/JDK-8133659
original patch pushed to 9: 
http://hg.openjdk.java.net/jdk9/dev/langtools/rev/caa3490d5aee
public review: http://cr.openjdk.java.net/~mcimadamore/8133659/

The 9 patch doesn't apply cleanly to 8u because of the changes around 
the Kind.java class (which has been converted into an enum in 9). 
Changes are only superficial though.

Thanks,
Maurizio