Use setTimeout for async work

.gitignore

@@ -1,5 +1,6 @@
 node_modules/
 dist/
+tmp/
 coverage/
 lib/**/*.d.ts
 .idea/

karma.conf.js

@@ -2,6 +2,8 @@
 
 var path = require('path');
 
+var fs = require('fs');
+
 var coverage = process.env.COVERAGE;
 
 // configures browsers to run test against
@@ -11,6 +13,12 @@ var browsers = (process.env.TEST_BROWSERS || 'ChromeHeadless').split(',');
 // use puppeteer provided Chrome for testing
 process.env.CHROME_BIN = require('puppeteer').executablePath();
 
+var tmpDir = path.join(__dirname, 'tmp');
+
+fs.mkdirSync(tmpDir, { recursive: true });
+
+var firefoxProfile = fs.mkdtempSync(path.join(tmpDir, 'firefox-profile'));
+
 var absoluteBasePath = path.resolve(__dirname);
 
 var suite = coverage ? 'test/coverageBundle.js' : 'test/testBundle.js';
@@ -35,6 +43,14 @@ module.exports = function(karma) {
 
     reporters: [ 'progress' ].concat(coverage ? 'coverage' : []),
 
+    customLaunchers: {
+      'FirefoxHeadless': {
+        base: 'Firefox',
+        flags: [ '-headless' ],
+        profile: firefoxProfile
+      }
+    },
+
     browsers,
 
     browserNoActivityTimeout: 30000,

lib/features/scheduler/Scheduler.js

@@ -59,23 +59,26 @@
 
 Scheduler.prototype._schedule = function(taskFn, id) {
 
-  const {
-    promise,
-    resolve,
-    reject
-  } = defer();
+  const deferred = defer();
+
+  const executionId = setTimeout(() => {
 
-  const executionId = requestAnimationFrame(() => {
     try {
-      resolve(taskFn());
+      this._scheduled[id] = null;
+
+      try {
+        deferred.resolve(taskFn());
+      } catch (error) {
+        deferred.reject(error);
+      }
     } catch (error) {
-      reject(error);
+      console.error('Scheduler#_schedule execution failed', error);
     }
   });
 
   return {
     executionId,
-    promise
+    promise: deferred.promise
   };
 };
 
@@ -96,7 +99,7 @@
 };
 
 Scheduler.prototype._cancel = function(scheduled) {
-  cancelAnimationFrame(scheduled.executionId);
+  clearTimeout(scheduled.executionId);
 };
 
 /**
@@ -108,17 +111,12 @@
  */
 function defer() {
 
-  let resolve;
-  let reject;
+  const deferred = {};
 
-  const promise = new Promise((_resolve, _reject) => {
-    resolve = _resolve;
-    reject = _reject;
+  deferred.promise = new Promise((resolve, reject) => {
+    deferred.resolve = resolve;
+    deferred.reject = reject;
   });
 
-  return {
-    promise,
-    resolve,
-    reject
-  };
+  return deferred;
 }