The new frame type is inteneded to represent native C++ stack frames.
JS code may sometimes make calls to helper native functions that do not
provide any special stack layout besides the return address and frame pointer.

Currently the stack iterator bails out when it sees an unknown frame.
The patch allows the iterator to unwind stacks having such frames.

BUG=chromium:768540

Change-Id: I9c273c7015695a6733c0a0c52b522fca7b25de0d
Reviewed-on: https://chromium-review.googlesource.com/794991
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50058}