RFR: JDK-8306112 Implementation of JEP 445: Unnamed Classes and Instance Main Methods (Preview) [v20]

[Jim Laskey]

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

Jim Laskey has updated the pull request incrementally with one additional commit since the last revision:

  Improving error recovery in presence of less important syntactic errors in top-level methods and fields.
  
  Author: Jan Lahoda <jlahoda at openjdk.org>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13689/files
  - new: https://git.openjdk.org/jdk/pull/13689/files/8ccb9502..cfac821a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13689&range=19
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13689&range=18-19

  Stats: 32 lines in 4 files changed: 24 ins; 0 del; 8 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