Remove dependence on Node process

[rigelk]

Since 8157951#diff-748aab44419901d221371c9f7c2e2c4bf84e42df649e5f65a279bf139ebbbf63R69, we rely on the existence of process and especially process.hrtime to get timestamps. However this leads to unrecoverable exceptions when used in browsers.

The function should either be shimmed or replaced with a browser-equivalent.