RFR: 8268333: javac crashes when pattern matching switch contains default case which is not last

[Jan Lahoda]

The pattern matching switch desugaring should recognize cases where there is `default` case followed by a type pattern case, and not replace the type pattern with another `default`.

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Commit messages:
 - 8268333: javac crashes when pattern matching switch contains default case which is not last

Changes: https://git.openjdk.java.net/jdk/pull/4397/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4397&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268333
  Stats: 30 lines in 2 files changed: 28 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4397.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4397/head:pull/4397

PR: https://git.openjdk.java.net/jdk/pull/4397