Step 2 - Setup `useFakeDate` by default in Jest

• Step 1 - Add fake_date test helper
• Step 2 - Setup useFakeDate by default in Jest
• Step 3 - Update default fake date to match rspec fixtures
• Step 3 - Add helper for useFixturesFakeDate

What does this MR do?

This MR sets up useFakeDate by default in our Jest environment

spec/frontend/helpers/fake_date.js

@@ -6,24 +6,28 @@ const RealDate = Date;
 const isMocked = val => Boolean(val.mock);
 
 export const createFakeDateClass = ctorDefault => {
-  const defaultDate = new RealDate(...ctorDefault);
-  const defaultApplyDate = RealDate(...ctorDefault);
-
   const FakeDate = new Proxy(RealDate, {
     construct: (target, argArray) => {
-      return argArray.length ? new RealDate(...argArray) : defaultDate;
+      const ctorArgs = argArray.length ? argArray : ctorDefault;
+
+      return new RealDate(...ctorArgs);
     },
     apply: (target, thisArg, argArray) => {
-      return argArray.length ? RealDate(...argArray) : defaultApplyDate;
+      const ctorArgs = argArray.length ? argArray : ctorDefault;
+
+      return RealDate(...ctorArgs);
     },
     // We want to overwrite the default 'now', but only if it's not already mocked
     get: (target, prop) => {
       if (prop === 'now' && !isMocked(target[prop])) {
-        return () => defaultDate.getTime();
+        return () => new RealDate(...ctorDefault).getTime();
       }
 
       return target[prop];
     },
+    getPrototypeOf: target => {
+      return target.prototype;
+    },
     // We need to be able to set props so that `jest.spyOn` will work.
     set: (target, prop, value) => {
       // eslint-disable-next-line no-param-reassign