RFR: JDK-8263684: Avoid wrapping into BufferedWriter twice [v2]

[Jonathan Gibbons]

> Please review a trivial fix to avoid creating an unnecessary `BufferedWriter`.
> 
> `noreg-trivial` (or `noreg-cleanup` : take your pick). Either way, no test.

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  address review feedback

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4080/files
  - new: https://git.openjdk.java.net/jdk/pull/4080/files/938ca902..11be026f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4080&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4080&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4080.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4080/head:pull/4080

PR: https://git.openjdk.java.net/jdk/pull/4080