RFR: 8037397: Lost nested character class after intersection && [v3]

[Ian Graves]

> Bug fix with the intersection `&&` operator in regex patterns. In JDK-8037397, some character classes on the right hand side of the operator are dropped in cases where nested `[..]` classes are used with non "nested" ones.

Ian Graves has updated the pull request incrementally with one additional commit since the last revision:

  Adding a test.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3291/files
  - new: https://git.openjdk.java.net/jdk/pull/3291/files/2a783a1e..9a46443d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3291&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3291&range=01-02

  Stats: 35 lines in 1 file changed: 34 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3291.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3291/head:pull/3291

PR: https://git.openjdk.java.net/jdk/pull/3291