Here's a list of usages of `base.outer_window` that may be impacted by the change and my analysis/fixes. Note that I specifically did not look for `document->outer_window` since that one was already holding it forever, so it's out of scope for this MR (whether it's correct or not, the behavior is the same after this MR).
I also didn't consider some cases that already **did not check** for it being NULL or not, because they would have crashed earlier before anyway (they'd still crash now if outer window gets killed, but it's out of scope of the MR as I said). For those that says "Handled" it means I've added checks so that the behavior is same as before, i.e. detached inner windows behave as if outer window is NULL.
* `htmldoc.c/HTMLDocument_get_mimeType`: Changed so it doesn't rely on outer window. * `htmldoc.c/HTMLDocument7_get_defaultView`: This is actually fixed by these patches. * `htmlform.c/HTMLFormElement_submit`: Handled. * `htmlstorage.c/send_storage_event`: Fixed in a separate patch with tests, since it follows the outer window. * `htmlwindow.c/check_target_origin`: This (along with many other methods) can't have it NULL anymore or detached, since the caller must hold a ref to the outer window, and they're not called from our objects holding ref to inner window only. * `htmlwindow.c/HTMLWindowSP_QueryService`: This uses the outer window to obtain the browser and the doc obj, so it's fine. * `mutation.c/set_document_mode`: Handled. * `navigate.c/BindCallbackRedirect_Redirect`: Handled. * `navigate.c/nsAsyncVerifyRedirectCallback_OnRedirectVerifyCallback`: Handled. * `navigate.c/nsChannelBSC_init_bindinfo`: Uses the outer window to obtain the browser and doc obj to set a flag, so it's harmless and probably correct this way. * `navigate.c/handle_navigation_error`: Handled. * `navigate.c/handle_extern_mime_navigation`: Handled. * `omnavigator.c/OmHistory_get_length`: This is actually fixed by these patches. * `script.c/ActiveScriptSite_GetItemInfo`: Handled. * `script.c/ActiveScriptSiteWindow_GetWindow`: Handled.