With the changes made in PR 5169 to enable quicker display of the File size, `setFileSize()` can now be called during file loading. This function parses *and* localizes the file size, where the l10n is a synchronous operation.
This patch:
* Re-factors `setFileSize()` to *only* update `rawFileSize`, and moves parsing and fetching of the l10n string to a separate method that isn't called until the Document Properties dialog is actually opened.
* Adds a couple of checks to make sure that `rawFileSize` is set to a positive number.
* Removes the `fileName` and `fileSize` properties. Since they are parsed every time the Document Properties dialog is opened, it doesn't seem necessary to cache them.
Currently the File size field in the Document Properties dialog isn't set until `PDFView.pdfDocument.getDownloadInfo()` is resolved. If the Document Properties dialog is opened while a PDF file is loading with range requests, this leads to the less desirable situation where all fields *except* File size are available.
In cases where `PDFView.open()` is called with the `args` parameter defined, and `args` contains the property `length`, we actually know the File size when the PDF file begins to load. (This is usually the case when ranged loading is used in the Firefox addon/built-in version.)
Hence we can use `args.length` to set the File size immediately when `PDFView.open()` is called, resulting in a better user experience.
