RFR: 8299255: Unexpected round errors in FreetypeFontScaler [v2]

[Toshio Nakamura]

> In 'Java_sun_font_FreetypeFontScaler_createScalerContextNative', 'context->transform.xx' and '.yy' values are sometimes 65535 instead of 65536. There are unintentional double and float conversions. It may be no real harm, but I'd like to fix it.
> 
> Problem case:
> context->transform.xx=**65535** yx=0 xy=0 yy=**65535** ptsz=46.590909 dmat[0]=46.590909 (float)dmat[0]=46.59090**8**
> 
> Normal case:
> context->transform.xx=65536 yx=0 xy=0 yy=65536 ptsz=18.000000 dmat[0]=18.000000 (float)dmat[0]=18.000000
> 
> Test: jdk_desktop on Linux x86_64 had no regression issues.

Toshio Nakamura has updated the pull request incrementally with one additional commit since the last revision:

  Adding a testcase

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11763/files
  - new: https://git.openjdk.org/jdk/pull/11763/files/09ed05de..6a64ad71

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11763&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11763&range=00-01

  Stats: 69 lines in 1 file changed: 69 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11763.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11763/head:pull/11763

PR: https://git.openjdk.org/jdk/pull/11763