Core: Adjust comments & tests after dropping Safari 6 support

Support comments that mentioned only Safari < 7 were checked & updated
to account for bugs existing in newer versions as well; Safari 6 support
test results were removed.

(cherry-picked from 93bee4701d)

Refs gh-2482

src/event.js

@@ -572,7 +572,7 @@ jQuery.event = {
 			event.target = originalEvent.srcElement || document;
 		}
 
-		// Support: Safari 6.0+
+		// Support: Safari 6-8+
 		// Target should not be a text node (#504, #13143)
 		if ( event.target.nodeType === 3 ) {
 			event.target = event.target.parentNode;

src/offset.js

@@ -215,6 +215,7 @@ jQuery.each( { scrollLeft: "pageXOffset", scrollTop: "pageYOffset" }, function(
 	};
 });
 
+// Support: Safari<7-8+, Chrome<37-44+
 // Add the top/left cssHooks using jQuery.fn.position
 // Webkit bug: https://bugs.webkit.org/show_bug.cgi?id=29084
 // getComputedStyle returns percent when specified for top/left/bottom/right