The other browsers have been moving too slowly in their update cycles and it is starting to show. The difference this time is that WebKit is open source.
using -webkit- prefixes but not the -o- and -moz- counterparts is just very bad CSS and has nothing to do with slow update circles anywhere.
In terms of what is delivered in each update, Chrome is ahead. For instance, IndexedDB in Firefox at one stage was an order of magnitude slower than Chrome for several months and this may still be the case, Mozilla's implementation being based on SQLite, with Chrome on LevelDB. There is the dubious history of WebSQL, and the FileSystem API. Many of the new useful CSS features have taken far longer in Firefox. And then there is the similar rendering across WebKit browsers. Firefox renders some things like line-height completely differently.