[8u-dev] Request for review: 8160156: javac is generating let expressions unnecessarily

[Vicente-Arturo Romero-Zaldivar]

Please review the following backport to 8udev. The jtreg test is 
different from the jdk9 version.

jdk9 bug: https://bugs.openjdk.java.net/browse/JDK-8160156
backport: https://bugs.openjdk.java.net/browse/JDK-8163866
open webrev: http://cr.openjdk.java.net/~vromero/8160156/webrev.00/
jdk9 patch: http://hg.openjdk.java.net/jdk9/dev/langtools/rev/88cc9b782624

Thanks,
Vicente