Fixing JCK failures caused by the new grapheme implementation. The length of a CharSequence should return the `endIndex`, not `endIndex - beginIndex`.
------------- Commit messages: - 8294008: Graphme implementation of setText() throws IndexOutOfBoundsException Changes: https://git.openjdk.org/jdk/pull/10349/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10349&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8294008 Stats: 6 lines in 2 files changed: 5 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/10349.diff Fetch: git fetch https://git.openjdk.org/jdk pull/10349/head:pull/10349 PR: https://git.openjdk.org/jdk/pull/10349
