feat: Add a version class to the player (#4320)

Adds `vjs-v6` class so you can target that version of Video.js.

src/js/player.js

@@ -442,6 +442,11 @@ class Player extends Component {
     // Make player easily findable by ID
     Player.players[this.id_] = this;
 
+    // Add a major version class to aid css in plugins
+    const majorVersion = require('../../package.json').version.split('.')[0];
+
+    this.addClass(`vjs-v${majorVersion}`);
+
     // When the player is first initialized, trigger activity so components
     // like the control bar show themselves if needed
     this.userActive(true);

test/unit/player.test.js

@@ -1617,3 +1617,12 @@ QUnit.test('options: plugins', function(assert) {
   player.dispose();
   Plugin.deregisterPlugin('foo');
 });
+
+QUnit.test('should add a class with major version', function(assert) {
+  const majorVersion = require('../../package.json').version.split('.')[0];
+  const player = TestHelpers.makePlayer();
+
+  assert.ok(player.hasClass('vjs-v' + majorVersion), 'the version class should be added to the player');
+
+  player.dispose();
+});