RFR: 8244146: javac changes for JEP 306 [v2]

[Joe Darcy]

> 8244146: javac changes for JEP 306

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Respond to review feedback.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3831/files
  - new: https://git.openjdk.java.net/jdk/pull/3831/files/a0a68baa..ec4d163a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3831&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3831&range=00-01

  Stats: 19 lines in 9 files changed: 10 ins; 1 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3831.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3831/head:pull/3831

PR: https://git.openjdk.java.net/jdk/pull/3831