RFR: 8294293: Remove unused _width and _newlines field in outputStream [v2]

[Johan Sjölen]

> 1. `_width` is unused so I deleted it
> 2. `_newlines` was used in one place, and only to check if any new lines had been seen. I removed `_newlines` and instead used `update_position`'s unused return value to indicate whether any newlines has been seen. This required expanding the call of `xmlTextStream::write` in `defaultStream`.
> 
> This removes some cruft from `outputStream` and saves us 8 bytes on the size of `outputStream`.
> 
> I also noted that `_position` isn't number of chars into a line, but rather a "visual position". It's a bit surprising, which is why I added this comment. This can be seen in the `\t` case in `update_position`.

Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:

  Remove include

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10411/files
  - new: https://git.openjdk.org/jdk/pull/10411/files/18847c61..11977a50

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10411&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10411&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10411.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10411/head:pull/10411

PR: https://git.openjdk.org/jdk/pull/10411