fix: hangs in an iframe when it redirects to a cross-domain site

[wentwrong]

Purpose

TestCafe hangs when click in an iframe redirects to a page on a different domain. It occurs due to the cross-origin iframe's driver not able to read the pending actions from the ContextStorage of its parent and because of that the driver doesn't send the "ready" driver status and TestCafe hangs.

Approach

In the cross-domain iframe we should check that the parent doesn't have pending actions as well. Because the iframe and its parent with different origins doesn't share a common sessionStorage (its used under the hood of ContextStorage), we should send the message to check if there're some pending actions in the parent's driver.

References

Fixes #4232

Pre-Merge TODO

• Write tests for your proposed changes
• Make sure that existing tests do not fail

[miherlosev]

I will finish this PR.