Profiler improvements

Profiler improvements

(1) --prof-cpp: Collects ticks like --prof, but ignores code creation events to reduce distortion (so all JS ticks will be "unaccounted"). Useful for profiling C++ code.
(2) --timed-range flag for tick processor: Ignores ticks before the first and after the last call to Date.now(). Useful for focusing on the timed section of a test.

Review URL: https://codereview.chromium.org/802333002

Cr-Commit-Position: refs/heads/master@{#26168}