Safari doesn't run on Windows or Linux. WebKit does run outside of Apple's environment but no major browser uses it which means you are left Firefox, a Blink based browser or a WebKit browser that 5 people use.
Safari runs on many, many millions of various Apple devices though, and I think that more than qualifies it as a major/mainstream browser, and the same for Webkit as a mainstream engine... especially considering Safari's market share is ~5x higher than Firefox. You may disagree though, and that's ok.
Webkit is not controlled by Google and powers Safari as well as some smaller browsers and many other applications.
Safari doesn't run on Windows or Linux. WebKit does run outside of Apple's environment but no major browser uses it which means you are left Firefox, a Blink based browser or a WebKit browser that 5 people use.
Safari runs on many, many millions of various Apple devices though, and I think that more than qualifies it as a major/mainstream browser, and the same for Webkit as a mainstream engine... especially considering Safari's market share is ~5x higher than Firefox. You may disagree though, and that's ok.