Even in optimized code we can utilize the various load and store IC
trampolines to save code space when it's an IC in the outermost
function, as in that case the trampoline can just take the vector
from the parent's frame.

BUG=v8:5267

Review-Url: https://codereview.chromium.org/2776073005
Cr-Commit-Position: refs/heads/master@{#44226}