improve SkParagraph's bench accuracy

Call onDraw in onDelayedSetup to warm up the glyph cache
otherwise nanobench will mis-caclulate the loop count.

This change also reduces the variability of the benchmark.

Change-Id: I5f3f2167cc78b996fcb589644b70622d18af240b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/386816
Commit-Queue: Mike Reed <reed@google.com>
Auto-Submit: Herb Derby <herb@google.com>
Reviewed-by: Mike Reed <reed@google.com>
1 file changed