- console.assert now fails properly
- console.trace dumps a low-level stack trace
- console.time/End dumps a timer event to the log file
- console.timeStamp dumps a timer event to the log

Drive-by-fixes:
- simplify test-log.cc
- fix test-log.cc log parser JS helper
- always start the default timer int the logger

Change-Id: I0bb26b9410a4e0d1d5bc8621d8b2243922fe3f29
Reviewed-on: https://chromium-review.googlesource.com/702459Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48531}