Fix unreliable image streaming

Return the request stream directly after pausing it, instead of setting up an
undocumented 'request' listener. Error handling didn't seem to work for
stream-based requests. This led to some image requests never finishing
whenever there was some issue, which in turn prevented the remainder of the
tasks from ever running.

Change-Id: Ic69863791ef4179de1d61295ec85cb76e5b13e16
Extra logging in jenkins

Change-Id: I6926c0e1f1fd509bda171ec5059ac561f6b4a2dc
Tighter query for images.

Use a more-precise selector query for <img> tags within figures, better
matching the Parsoid DOM spec.

Change-Id: I7d42eaa8ec02d4a1066e9344a18f2263e2efbfd4
Use default papersize when bundling.

We use the de facto convention established by `libpaper` on linux.
On other platforms, `/etc/papersize` probably doesn't exist, and so
we don't specify a papersize in the metabook.

An explicit papersize in the metabook json overrides the default.

Bug: 68836
Change-Id: If9657503522a95fc3c30867c71526415a3bc9d15
Merge "Tighter query for images."