Implement the missing bits for named access to Number values, which is
basically always done on the Number prototype.  Crankshaft only deals
with Number primitives in the polymorphic case, while we generally
support Numbers even for monomorphic access.

R=jarin@chromium.org
BUG=v8:4470
LOG=n

Review URL: https://codereview.chromium.org/1425293004

Cr-Commit-Position: refs/heads/master@{#31731}