This not a reply. It's a reinstatement of the urgency to resolve this continued (and serious) problem. Someone, please, reply to my original post ASAP.

Nope, it will not work.

The Android version of Firefox does not have the built-in (JavaScript-based) PDF viewer. The developers have a list of speed and memory usage fixes that need to be completed before it will be added.

If what you both say is true (I have no evidence to refute this problem being true or false), then why did Firefox developer (Mozilla) pull the experimental add-on PDF Viewer BEFORE FIXING THE ANDROID VERSION that actually worked for me on my Samsung Galaxy S3? This problem & the absense of any forseeable remedy makes absolutely no sense to the millions of Android users.

Maybe the add-on had those same problems?? Sorry, I don't know the answer to that one.