These tags are preserved by the Closure compiler and vulcanize in order
to serve the license notices embedded in the outputs. In a standalone
Gerrit server, these license are also covered in the LICENSES.txt served
with the documentation. When serving PG assets from a CDN, it's less
obvious what the corresponding LICENSES.txt file is, since the CDN is
not directly linked to a running Gerrit server. Safer to embed the
licenses in the assets themselves.
Change-Id: Id1add1451fad1baa7916882a6bda02c326ccc988
