This CL adds global state management
methods into the App Class. Thus, make it
easier to control global state of the web app.

Bug: v8:10667, v8:10644

Change-Id: I9e37c3e851a3912ebc6c672eb4372f77d20a989c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2300482
Commit-Queue: Zeynep Cankara <zcankara@google.com>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68887}