Fix breakage regarding (set|clear)Immediate

Author: eps1lon

scripts/jest/setupTests.js

@@ -310,4 +310,10 @@ if (process.env.REACT_CLASS_EQUIVALENCE_TEST) {
   };
 
   require('jasmine-check').install();
+
+  if (typeof window !== 'undefined') {
+    // FIXME: Possible bug in jest 27 + legacy fake timers?
+    delete window.setImmediate;
+    delete window.clearImmediate;
+  }
 }