SetForceInline flag is no longer used. This flag was added for
inlining some of the javascript builtins. They are now ported to
TurboFan builtins. This cl removes SetForceInline runtime function
and the corresponding bits in the SharedFunctionInfo. Also update
inlining heuristics to not look for this bit.

Bug: v8:6682
Change-Id: Ie8df9648332b765a556e24609c38b4e55b810527
Reviewed-on: https://chromium-review.googlesource.com/668436Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48065}