Bug 1031612 - In PDF Viewer, the buggy XMP title "Untitled" overrides th...

...e document info title

Reordered to make sure if info['Title'] exists, assign pdfTitle to it.
> if (title.toLowerCase() !== 'untitled') {

I would disagree with checking a lower case equivalent, but I would certainly expect to see a comment with explanation why we are doing the comparison.