Add xit snippet for javascript testing

vim/snippets/javascript.snippets

@@ -8,6 +8,9 @@ snippet it "it (js)"
 		$0
 	});
 
+snippet xit "xit (js)"
+	xit('${1:description}')
+
 snippet bef "before each (js)"
 	beforeEach(() => {
 		$0