Updated the style of the examples

* const/let instead of var
* classes
* pass our own eslint checks

lib/jasmine-core/example/src/Player.js

@@ -1,22 +1,22 @@
-function Player() {
-}
-Player.prototype.play = function(song) {
-  this.currentlyPlayingSong = song;
-  this.isPlaying = true;
-};
-
-Player.prototype.pause = function() {
-  this.isPlaying = false;
-};
-
-Player.prototype.resume = function() {
-  if (this.isPlaying) {
-    throw new Error("song is already playing");
+class Player {
+  play(song) {
+    this.currentlyPlayingSong = song;
+    this.isPlaying = true;
   }
 
-  this.isPlaying = true;
-};
+  pause() {
+    this.isPlaying = false;
+  }
 
-Player.prototype.makeFavorite = function() {
-  this.currentlyPlayingSong.persistFavoriteStatus(true);
-};
+  resume() {
+    if (this.isPlaying) {
+      throw new Error('song is already playing');
+    }
+
+    this.isPlaying = true;
+  }
+
+  makeFavorite() {
+    this.currentlyPlayingSong.persistFavoriteStatus(true);
+  }
+}

lib/jasmine-core/example/src/Song.js

@@ -1,7 +1,6 @@
-function Song() {
+class Song {
+  persistFavoriteStatus(value) {
+    // something complicated
+    throw new Error('not yet implemented');
+  }
 }
-
-Song.prototype.persistFavoriteStatus = function(value) {
-  // something complicated
-  throw new Error("not yet implemented");
-};