When running in debug, or in continuous integration that is not setup
for performance testing, default to not collecting performance metrics
to avoid failures due to slow or high-variability tests (default
max_stddev = 10% in xctest). Instead, run the measured block once and
skip the timing code. This has the nice side effect of speeding up test
runs in debug builds.
Add remaining foldingRange protocol capabilities
Sending offset data to folding requests
FoldingRange test
Support folding comments
Add test for folded comments
