RFR: 8306308: (ch) Writer created by Channels::newWriter may lose data

[Brian Burkhalter]

Change `Channels.newWriter` to return a `Writer` created by first wrapping the `WritableByteChannel` in an `OutputStream` using `Channels.newOutputStream` and then wrapping the result in an `OutputStreamWriter`. With this change in place, the problems reported in the issue do not occur.

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

Commit messages:
 - 8306308: (ch) Writer created by Channels::newWriter may lose data

Changes: https://git.openjdk.org/jdk/pull/16207/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16207&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306308
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16207.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16207/head:pull/16207

PR: https://git.openjdk.org/jdk/pull/16207