Conflict in the keyboard interactions for a date picker

Hi,

Trying to implement the recommended keyboard interaction for the date
picker, I have encountered a conflict between the recommendation and
browsers keyboard shortcuts.

The recommendation is to use Ctrl + Page Up / Down to "Moves to the same
date in the ( previous / next ) year". However many browsers (Firefox and
Chrome) use this key combination to toggle through the opened tabs.

One way to possibly resolve this is to recommend that the behavior be
matched to not only Ctrl but also to Alt and Shift since those are not
mapped to anything in this context.