The effect control linearizer runs off-thread and needs the ToNumber
call descriptor. Add a hack to create this on the main thread to
ensure off-thread's don't race on it's construction. Also add a
DCHEK to the CallInterfaceDescriptor to ensure they are always
initilaized on the main thread.

Review-Url: https://codereview.chromium.org/2168843003
Cr-Commit-Position: refs/heads/master@{#37973}