RFR: 8305582: Compiler crash when compiling record patterns with var [v2]

[Aggelos Biboudis]

> While `var` is not allowed in record pattern position the compiler was not checking it. This PR address this issue, by introducing the relevant error symbols and error types.
> 
> e.g., `if (o instanceof ColoredPoint(var(var x, var y), var c)) { }`

Aggelos Biboudis has updated the pull request incrementally with one additional commit since the last revision:

  Add more tests

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13331/files
  - new: https://git.openjdk.org/jdk/pull/13331/files/d5e1624d..c13be556

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13331&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13331&range=00-01

  Stats: 9 lines in 2 files changed: 7 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13331.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13331/head:pull/13331

PR: https://git.openjdk.org/jdk/pull/13331