There is a print in AstNumbering which needs to dereference the string
containing the function name, which clashes with the disallowed handle
reference scope used to allow ast-numbering to run off-thread.

This could be fixed by pushing the print out of this function, and
somehow propagating disable_crankshaft_reason out of the visitor, but in
reality this check will soon be removed anyway, and until it is this
function will be on the main thread, so we may as well just hack it.

Review-Url: https://codereview.chromium.org/2653953006
Cr-Commit-Position: refs/heads/master@{#42711}