Don't over simplify near-colinear vertices

This adds an error variable that keeps track of the total distance from
the simplified line, and includes it when determining if we should
keep the next point. Using a sum of line distance is just a heuristic
but seems to address the current case of over simplification while
allowing us to keep a greedy strategy.

Bug: chromium:1086705
Change-Id: I29e21724db6b30495c2934e376a5e4d787c846a9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/309328
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
4 files changed