Don't show CC0 license on Only Me annotations

The js-polyfills library is a nice one. It provides enough for
PhantomJS and it provides the URL polyfill. However, we keep core-js
since for production it's better to have the lightweight requirement
of just the es6.promise module without global namespace pollution.

We tolerate pollution of the global namespace for browsers with a
broken or absent URL constructor implementation.

Annotating under IE10 works now!

With this change, there is no longer any patching of the global
object from node-iterator-shim. I believe that's the end of all the
global patching in all of our code. Only Annotator and jQuery remain
in the global space, but both are removed with noConflict.

Nice and clean.

The scroll-into-view module already depends on raf, it's tiny, and
this lets us drop the bundled vendor lib. It also makes the guest
and host tests more consistent.

This lets us require Promise without polluting the global namespace.
Additionally, the core-js implementation has immediacy hacks that
will make it more performant for IE.

This also caught some issues with our async tests.

And hey, it's about 700 bytes smaller, too!

This fixes the dialogs to have the same space around them as the
main content. It's a bit like re-introducing the #wrapper, but with
a class this time that's re-used by the topbar for sizing its content.

This is a little bit confusing, but it is better this way. It's
confusing because webassets doesn't set the compass image directory,
so the paths still have an "images/" prefix. However, the cssrewrite
filter uses the output URL from webassets and that will be an absolute
URL at request time. The compass filter uses only the base URL from the
environment configuration, which is relative. Letting compass do the
rewriting therefore results in merged compass files having correct, but
relative, paths regardless of whether the assets are generated at the
command line or at request time. This should make it possible to pre-
compile the assets before the first request without generating bad
URLs, and to virtual host the application under multiple URLs.

In order to upgrade clean-css it is necessary to import the filter
definition from the future version of webassets. This version takes
extra arguments in the filter configuration, allowing us to disable
the advanced optimizations that became the default in 3.0+ but that
breaks some of our styles.

Fix #2452

This lets the top bar set a font size for its inner content while
still matching the padding to the rest of the page.

This is much neater. Since the scale origin is the center of the
icon this will scale around the center of the line, avoiding any
messy vertical alignment nonsense. This works much better than
vertical-align middle and font-size because vertical-align middle
puts the center of the element at the x-height, rather than the
middle of the line. This is much cleaner.

Lay out the search bar and the top bar using flexbox because the
vertical centering is much better and easier using flexbox instead
of floats and line heights.

As long as we're using only features easily supported in the 2012
and final spec the -ms prefix gets us IE10. All other browsers we
care about should be supported already by the compass mixins.

- Use .btn wherever we use .btn-clean

- No border on .btn-clean

This is necessary for true vertical alignment.
See http://christopheraue.net/2014/03/05/vertical-align/

- Convert some units to ems

- Remove extraneous rules

- Remove extraneous integer parts of floats

Fix https://github.com/hypothesis/h/issues/2429

Oops

Replace the use of the websocket for scrollback with a simple
pagination scheme.