RFR: 8349699: XSL transform fails with certain UTF-8 characters on 1024 byte boundaries [v3]

[Joe Wang]

> Fix an edge case in the patch for JDK-8207760.

Joe Wang has updated the pull request incrementally with one additional commit since the last revision:

  add tests verifying invalid sequence; also add tests to verify cases where the pairs are at the edges or anywhere in the text

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23623/files
  - new: https://git.openjdk.org/jdk/pull/23623/files/98d5dfc3..19dd8a23

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23623&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23623&range=01-02

  Stats: 121 lines in 1 file changed: 105 ins; 12 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/23623.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23623/head:pull/23623

PR: https://git.openjdk.org/jdk/pull/23623