Before Turbofan/Ignition it was possible to use external profilers to
sample running V8/Node.js processes and generate reports/FlameGraphs
from that. It's still possible to do so, but non-optimized JavaScript
functions appear in the stack as InterpreterEntryTrampoline. This commit
adds a runtime flag which makes interpreted frames visible on the
process' native stack as distinguishable functions, making the sampled
data gathered by external profilers such as Linux perf and DTrace more
useful.

R=bmeurer@google.com, franzih@google.com, jarin@google.com, yangguo@google.com

Bug: v8:7155
Change-Id: I3dc8876aa3cd9f1b9766624842a7cc354ccca415
Reviewed-on: https://chromium-review.googlesource.com/959081
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52533}