Moves scrollPageIntoView to the PDFViewer.
Adds css import preprocessing
Merge pull request #5361 from yurydelendik/movescrollinto

Moves scrollPageIntoView to the PDFViewer.
Move text_layer_builder and pdf_viewer styles out
Merge pull request #5362 from yurydelendik/css-import

Use CSS import to separate pdfviewer styles
Rename FontFace to FontFaceObject

This name clashes with the FontFace constructor from the Font Loading CSS module:
http://dev.w3.org/csswg/css-font-loading/#font-face-constructor
Packages PDFViewer as a UI component.
Introduces 'pagesinit' event.
Merge pull request #5363 from yurydelendik/pdfviewecomponent

Packages PDFViewer as a UI component.
Use Font Loading API if available

http://dev.w3.org/csswg/css-font-loading/
Fixes enabling pdfBug
Merge pull request #5367 from yurydelendik/fixpdfbug

Fixes enabling pdfBug
Fixes examples comments.
Merge pull request #5366 from Rob--W/use-font-loader-api

Use font loader api
Add a page loading indicator to the page number input
Add updated loading-small.png (and corresponding Retina) asset
Fixes printing regression a10fde1
Merge pull request #5368 from yurydelendik/fixprintcss

Fixes printing regression a10fde1
Merge pull request #4150 from Snuffleupagus/issue-3990

Add a page loading indicator to the page number input
Fix inconsistencies in the preference names used by PDFViewerApplication

Since `preferenceSidebarViewOnLoad` is an enumeration value, it seems better to initialize it with the default one instead of a boolean.
`preferencesPdfBugEnabled` uses a superfluous "s", which is a typo I made when I introduced it.