This lowers JSCreateArguments nodes within inline (i.e. non-outermost)
frames that create "unmapped arguments objects" to inline allocations.

The arguments count as well as each value is statically known and can be
directly stored into the arguments object. Note that the object is still
context-dependent and the map is loaded from the current context. The
object size is not taken into account for now, we might want to limit it
later though to keep code size bounded.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1412113004

Cr-Commit-Position: refs/heads/master@{#31550}