Add context option to reduce opList splitting

This is split out of: https://skia-review.googlesource.com/c/skia/+/143113 (Reduce arbitrary opList splitting when sorting (take 3)).
It needs to be behind a context option because, without mini-flushes, it can cause OOM on smaller devices (e.g., Nexus7 and AndroidOne).

Change-Id: Icde3302bd033a9c4634bb0ca97c950456e73db7c
Reviewed-on: https://skia-review.googlesource.com/c/160763
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
6 files changed