WebKit will no longer release experimental features with prefixes (i.e. -webkit-font-smoothing) as many have found that this can actually quite harmful:
Over time this strategy has turned out not to work so well. Many websites came to depend on prefixed properties. They often used every prefixed variant of a feature, which makes CSS less maintainable and JavaScript programs trickier to write. Sites frequently used just the prefixed version of a feature, which made it hard for browsers to drop support for the prefixed variant when adding support for the unprefixed, standard version. Ultimately, browsers felt pressured by compatibility concerns to implement each other’s prefixes.
Instead, experimental features will be shipped behind a runtime flag. Meaning the new features will be available, unprefixed, in development versions of the browser (i.e. “Technology Preview versions” or “Nightlies”).
WebKit is the last to jump on this wagon. Perhaps a few years from now, we’ll hardly use or think about prefixes at all.