Since we don't pass references to this constant to the DCHECKs any more
(see http://crrev.com/2524093002), the constant can now be initialized
in the header, reducing code size and increasing performance.

Before the mentioned change in CHECK/DCHECK, this caused link errors.

R=ishell@chromium.org
CC=jgruber@chromium.org
BUG=v8:5684

Review-Url: https://codereview.chromium.org/2541533002
Cr-Commit-Position: refs/heads/master@{#41450}