If you were designing a core business intranet app for a small business, and wanted it to be as responsive-feeling as possible, where the staff are indifferent to being stuck with a certain browser, would you design for Firefox, Chrome, or test more widely than you need to just to avoid lock-in? Are there other factors you'd consider before placing all your eggs in one browser basket or not?
For instance, does Chrome have any speed-related features that other browsers lack that would need Chrome to be targeted in a cross-browser-unfriendly way, and if it did, would it be worth designing around them?