If profiling is done with --log-source-code profview will now display
a "View source" link for each function in the tree view. Clicking this
will show a new source viewer, with sampled lines highlighted. See the
associated bug for screenshots.

This patch also fixes a bug in the profiler where the source info of
only the first code object for each function would be logged, and
includes some refactoring.

Bug: v8:6240
Change-Id: Ib96a9cfc54543d0dc9bef4657cdeb96ce28b223c
Reviewed-on: https://chromium-review.googlesource.com/1194231
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55542}