    Description: Nested iframes cannot have less sandbox restrictions than their most restrictive ancestor iframe.

This test is to verify script is allowed inside nested iframes if any of the conditions below are true
1. both parent sandbox and child sandbox have 'allow-scripts' token.
2. parent sandbox has 'allow-scripts' token and nested child iframe has no sandbox attribute.
3. parent iframe has no sandbox attribute and child iframe has sandbox='allow-scripts' token.
4. both parent and child iframes have no sandbox attribute.

Test Result | Test Assertion
Manual | Test passes if there is no red on the page.

Top-most iframe with sandbox="allow-scripts"
Top-most iframe without sandbox attribute