refine SkPath::approximateBytesUsed()

Instead of looking at point/verb/weight counts, add an
SkPathRef::approximateBytesUsed() using their reserve counts.

This shows SkPathBuilder::snapshot() can return more memory-efficient
SkPaths than SkPathBuilder::detach(), at the cost of a copy.

Change-Id: I4e208c41643480d7682daba6ac674ffa63c74de2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/326608
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Klein <mtklein@google.com>
4 files changed