This CL uses bits of the call count as flags according
to CallCountField and SpeculationModeField defined in
CallICNexus.

Bug: v8:7127
Change-Id: I3f64c1807d61410f9029b46b9a59a1fcaa5a0a3b
Reviewed-on: https://chromium-review.googlesource.com/808926
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49959}