[jdk17] RFR: JDK-8269150 Unicode \u005C not treated as an escaping backslash [v8]

[Jim Laskey]

> \u005C Unicode escape sequence not being treated as a backslash for general escape sequences.

Jim Laskey has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:

 - Merge branch 'master' into 8269150
 - Update UnicodeBackslash test to be easier to follow
 - Remove comment duplicated by merge
 - Merge branch 'master' into 8269150
 - Merge branch '8269150b' into 8269150
 - Use jdk15 logic
 - Proposed change
 - Merge branch 'master' into 8269150
 - Updated the test to include all combinations
 - Merge branch 'master' into 8269150
 - ... and 1 more: https://git.openjdk.java.net/jdk17/compare/68e5649b...3bc5789c

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/126/files
  - new: https://git.openjdk.java.net/jdk17/pull/126/files/cfc1614c..3bc5789c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=126&range=07
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=126&range=06-07

  Stats: 1312 lines in 71 files changed: 921 ins; 224 del; 167 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/126.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/126/head:pull/126

PR: https://git.openjdk.java.net/jdk17/pull/126