Adds new Guard[Type] common operator, which takes value and control
inputs and records a guaranty that a certain value has a certain type
in that control path.  This is some kind of ad-hoc SSI similar to what
we have to do in Crankshaft in some places.

Also introduces an ObjectIsNumber simplified operator, which checks
whether a certain value is a number (either a Smi or a HeapNumber).

This doesn't yet support transitioning stores to double fields, which
require support for allocating mutable heap numbers.

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

Review URL: https://codereview.chromium.org/1420283009

Cr-Commit-Position: refs/heads/master@{#31675}