Add better bounds checks for getTime to fix perf debug assert below

Due to rounding, we request a length slightly larger than the total
length in MeasureBench. This will be fixed in a following CL and there
will be another CL adding unit tests for bounds checking and other
problems.

Revert "Revert  386ba54 and  4ab47e0 : perf debug assert."

This reverts commit 69aaa5a49a10454d573cbd8c5d980029d78ae459.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2233983003

Review-Url: https://codereview.chromium.org/2233983003
2 files changed