For interpreted functions, use the optimized code slot in the feedback vector
to store an optimization marker (optimize/in optimization queue) rather than
changing the JSFunction's code object. Then, adapt the self-healing mechanism
to also dispatch based on this optimization marker. Similarly, replace SFI
marking with optimization marker checks in CompileLazy.

This allows JSFunctions to share optimization information (replacing shared
function marking) without leaking this information across native contexts. Non
I+TF functions (asm.js or --no-turbo) use a CheckOptimizationMarker shim which
generalises the old CompileOptimized/InOptimizationQueue builtins and also
checks the same optimization marker as CompileLazy and
InterpreterEntryTrampoline.

Change-Id: I6826bdde7ab9a919cdb6b69bc0ebc6174bcb91ae
Reviewed-on: https://chromium-review.googlesource.com/509716
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45901}