RFR: JDK-8306112 Implementation of JEP 445: Flexible Main Methods and Anonymous Main Classes (Preview) [v8]

[Jim Laskey]

> Add flexible main methods and anonymous main classes to the Java language.

Jim Laskey has updated the pull request incrementally with two additional commits since the last revision:

 - Anonymous main classes renamed to unnamed classes
 - Add test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13689/files
  - new: https://git.openjdk.org/jdk/pull/13689/files/a09a0a1b..ff7cd4c7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13689&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13689&range=06-07

  Stats: 314 lines in 14 files changed: 151 ins; 135 del; 28 mod
  Patch: https://git.openjdk.org/jdk/pull/13689.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13689/head:pull/13689

PR: https://git.openjdk.org/jdk/pull/13689