[8u20] Request for approval: 8029718: Should always use lambda body structure to disambiguate overload resolution

[Vicente-Arturo Romero-Zaldivar]

Hi,

This is a backport of a patch that is already in 9. The patch applies 
cleanly to 8u20.

Bug (8u20): https://bugs.openjdk.java.net/browse/JDK-8029718
Bug (9): https://bugs.openjdk.java.net/browse/JDK-8035431
jdk9 changeset: 
http://hg.openjdk.java.net/jdk9/dev/langtools/rev/90eb1e6bb784

Reviewed by Dan Smith, Jon Gibbons and Jan Lahoda

Thanks,
Vicente