Simplify k.w calculation in getConicKLM.

Additionally reformat the equations to better expose the symmetry.

BUG=skia:

Change-Id: If485cc7aeae97b89dedeb4d6b23efbe945036e3a
Reviewed-on: https://skia-review.googlesource.com/7000
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Dean McNamee <deanm@chromium.org>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed