Localize this string.

Change-Id: I88b205d36eede5e63af46f8581896d980b6aa27d
cp#1000072: Populate cache tables when updating all external links.

This way, even after the loaded doc shells get purged due to timeout,
we won't reload those external documents from disk again.  One caveat
is that we currently don't pre-populate empty cells even if they are
referenced by the host document.

Change-Id: I1de2987836bf2fc5d9d7044b406fb99faa534164