By this definition, all Mac Web browsers are broken, but you can fix the accidental Command-Q problem on an app-by-app basis by remapping Quit to something harder to accidentally type like Command-Shift-Q using the Keyboard pane in System Preferences.
Personally, for applications like my primary browser where intentionally quitting is overwhelmingly the exception rather than the rule, I remap Quit to Control-Command-Option-Shift-Q and rely on the fact that pressing Q while any application is selected in the Command-Tab switcher triggers its Quit command.
