Follow-up to #274, related to #257.

The call to the "passes rate test" algorithm should use `timeValue` rather
than `timestamp`: the former is what is stored in `PressureRecord.[[Time]]`,
so it makes sense to compare values that have been similarly coarsened and
converted to a relative time.

Follow-up to #274, related to #257.

The wording used in #274, which mentions platform-specific timestamps, made
more sense in the context of the Generic Sensor API spec, as multiple
platform-specific sensor APIs provide samples with timestamps in a
platform-specific format that needs to be converted.

Of the OS-provided telemetry APIs, however, only Windows optionally provides
samples with a timestamp. As such, it makes more sense to define a timestamp
using the monotonic clock's unsafe current time instead. Aditionally, the
accompanying note was rewritten to indicate that the same value should be
used for all globals, otherwise the same sample would end up with different
"raw" timestamps in different frames/workers.

…eck (#279)

Follow-up to #274, related to #257.

The call to the "passes rate test" algorithm should use `timeValue` rather
than `timestamp`: the former is what is stored in `PressureRecord.[[Time]]`,
so it makes sense to compare values that have been similarly coarsened and
converted to a relative time.

Follow-up to #274, related to #257.

The wording used in #274, which mentions platform-specific timestamps, made
more sense in the context of the Generic Sensor API spec, as multiple
platform-specific sensor APIs provide samples with timestamps in a
platform-specific format that needs to be converted.

Of the OS-provided telemetry APIs, however, only Windows optionally provides
samples with a timestamp. As such, it makes more sense to define a timestamp
using the monotonic clock's unsafe current time instead. Aditionally, the
accompanying note was rewritten to indicate that the same value should be
used for all globals, otherwise the same sample would end up with different
"raw" timestamps in different frames/workers.