[ts] ExtensionAPI: type check inspectedWindow api
[ts] ExtensionAPI: type check inspectedWindow api

Bug: 1219420
Change-Id: Ie12a7bf0f9c9b5bd17c1e668b8b87bd682a2566c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2987973
Commit-Queue: Philip Pfaffe <639a645feae3653b7aaefa0387217d375f2f82ff@chromium.org>
Reviewed-by: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend