This will allow sharing e.g. document cookie versions between the UI and
WebContent processes, and safely accessing those versions.
Core::AnonymousBuffer internally creates a minimum buffer of PAGE_SIZE
bytes. This is much more than the size of a single version, but this
affords us the opportunity to share multiple versions in a single buffer
between processes. With a PAGE_SIZE of 4096, we can share up to 512
versions in a single buffer.
