fix(net): Add 304 as successful request (#7963)

Fixes #7925

Author: avelad

lib/net/http_plugin_utils.js

@@ -32,7 +32,7 @@ shaka.net.HttpPluginUtils = class {
       requestType) {
     goog.asserts.assert(data, 'Data should be non-null!');
 
-    if (status >= 200 && status <= 299 && status != 202) {
+    if ((status >= 200 && status <= 299 && status != 202) || status == 304) {
       // Most 2xx HTTP codes are success cases.
       /** @type {shaka.extern.Response} */
       const response = {