Firefox 50 is all set to get Simplify Page feature, –which Google has removed from Chrome recently –the feature powered by Reader Mode removes the clutter so you can print the pages without unwanted ads or menus.
To try Simplify Page feature in Firefox browser, visit an article that supports the reader view, click on Firefox menu and select Print. Within the print preview, on the toolbar, check Simplify Page.
Firefox Simplify Page Keyboard Shortcut
FYI, Mozilla already offers keyboard shortcut for Firefox Reader View, it has also assigned one shortcut for Simplify Page feature, which you can now use to activate the feature without needing to use your mouse to check the box, here it is for Windows: it’s Alt +I.