[Refactor] Results: use this instead of self

Author: ljharb

lib/results.js

@@ -167,10 +167,9 @@ Results.prototype.createStream = function (opts) {
 };
 
 Results.prototype.push = function (t) {
-	var self = this;
-	$push(self.tests, t);
-	self._watch(t);
-	self.emit('_push', t);
+	$push(this.tests, t);
+	this._watch(t);
+	this.emit('_push', t);
 };
 
 Results.prototype.only = function (t) {