This patch purposely starts small, by removing IE-specific code from various JS/CSS files in the `web/` folder.
There's obviously lots of potential for additional clean-up, especially the removal of no longer necessary polyfills in `src/shared/compatibility.js`, however that will require some care considering that certain polyfills may also be necessary for e.g. Node.js or the Chromium-extension as well.
Generally speaking, once we start removing polyfills it's probably a good idea to consult the compatibility information on https://developer.mozilla.org/ and also https://caniuse.com/ first. (Deciding on the lowest supported Chromium version, for the extension, would also seem like a good idea.)
This builds on the scrolling mode work to add three buttons for joining
page spreads together: one for the default view, with no page spreads,
and two for spreads starting on odd-numbered or even-numbered pages.
This patch makes the naming consistent with the `TextLayerBuilder`, and also the new `AnnotationLayer`, and should thus help reduce possible confusion when working with the code.
Please note that the files were renamed using `git mv`, in order to preserve blame.
This is similar to the already existing, separate, CSS file used for the `textLayer`, and it's necessary in order for the `pageviewer` components example to actually show annotations correctly.
