message: refactor(upgrade): avoid using static inherited method
  Using `ParentInjectorPromise.all()` (which is a static method inherited
  from `SyncPromise`) causes Closure Compiler (or some related tool) to
  complain:
  ```
  TypeError: ...$packages$upgrade$src$common$src$downgrade_component_ParentInjectorPromise.all is not a function
  ```
  Switching to `SyncPromise.all()` (the static method on the parent class)
  to avoid this error.
  PR Close
diff: @@ -196,7 +196,11 @@ export function downgradeComponent(info: {
  wrapCallback(() => doDowngrade(pInjector, mInjector))();
  };
  - ParentInjectorPromise.all([finalParentInjector, finalModuleInjector])
  + // NOTE:
  + // Not using `ParentInjectorPromise.all()` (which is inherited from `SyncPromise`), because
  + // Closure Compiler (or some related tool) complains:
  + // `TypeError: ...$src$downgrade_component_ParentInjectorPromise.all is not a function`
  + SyncPromise.all([finalParentInjector, finalModuleInjector])
  .then(([pInjector, mInjector]) => downgradeFn(pInjector, mInjector));
  ranAsync = true;
  