…y_tracker.js`

This method is completely unused in the worker-thread, and it only has a single call-site in the main-thread.
By moving this helper into the `src/display/canvas_dependency_tracker.js` file, the size of the `gulp mozcentral` bundle is reduced by `1220` bytes.

…og during testing

This reduces duplication in the various integration-tests.

…cumentProperties` dialog

Improve test coverage for multi-page documents, to ensure that:
 - Unnecessary re-parsing is avoided where possible.
 - Rotation, in the viewer, is handled correctly.
 - Different page sizes are handled correctly.

If the active page is corrupt that currently results in the entire dialog being "blank", thus providing no information, which seems unfortunate and it's easy enough to only skip `pageSizeField` in that rare case.

Add a Content-Security-Policy to pdf.js' viewer.html (bug 1960363)

Move the `Util.scaleMinMax` helper into `src/display/canvas_dependency_tracker.js`

…re-tests

Add more integration-tests, with multi-page documents, for the `PDFDocumentProperties` dialog