It turns out that with the help of Code::Instruction{Start,End,Size}
helpers, we don't need custom profiler methods.

InstructionStream is now all-static.

Bug: v8:6666
Change-Id: I59e1d2d2cb72c128725a1ed03f11506d40e76224
Reviewed-on: https://chromium-review.googlesource.com/947973
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51837}