JDK 14 RFR of JDK-8231414: Mark various instance fields of javac internal types as transient

[Joe Darcy]

Hello,

As part of the on-going serialization cleanup (JDK-8160675 and related), 
please review

     JDK-8231414: Mark various instance fields of javac internal types 
as transient
     http://cr.openjdk.java.net/~darcy/8231414.0/

which marks instance fields of various serializable javac and javadoc 
internal types as transient. I got a clean local test run of all the 
langtools regression tests with this change applied.

Thanks,

-Joe