Does this belong in Core :: IPC or elsewhere? If yes, thank you for moving it.

Firefox 69.0a1 20190521094447 on Windows 8.1

Restore of a recently closed tab after the browser has been updated by another instance with this one running breaks the browser: content doesn't load.

Steps to reproduce:

1. Download a build which is updateable (= not the latest one), e.g. from http://ftp.mozilla.org/pub/firefox/nightly/2019/05/2019-05-20-21-55-28-mozilla-central/
2. Install it.
3. Launch it with -offline to prevent updates from getting installed.
4. Switch from auto-update to just notify about them.
5. Go online with the browser: Alt key > menu File > uncheck 'Work Offline'.
6. Load 4 pages from different domains.
7. Add a page as bookmark.
8. Keep the browser open.
9. Launch another Firefox instance from the console with the command line parameter -no-remote -P and create a new profile to use for this.
10. Let it install updates or request them to do so including the restart of this browser installing the updates.
11. Click the bookmark in the first browser with the mousewheel / middle mouse button.
    Actual result: page loads.
12. Close tab.
13. Close a tab opened at 6.
14. Press Ctrl+Shift+T to reopen it.
    Actual result:
    Action fails, no tab reopened.
15. Click the bookmark in the first browser with the mousewheel / middle mouse button.
    Actual result:
    Nothing happens.
16. Open a new tab and try to load a page.
    Actual result: Page never finishes loading.
17. Try to close the tab opened in 16.
    Actual result: Tab not closed.

From the error console:
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
construct chrome://global/content/elements/browser-custom-element.js:1048
connectedCallback chrome://global/content/elements/browser-custom-element.js:315
_insertBrowser chrome://browser/content/tabbrowser.js:2104
addTab chrome://browser/content/tabbrowser.js:2535
addTrustedTab chrome://browser/content/tabbrowser.js:2251
ssi_undoCloseTab resource:///modules/sessionstore/SessionStore.jsm:2728
ss_undoCloseTab resource:///modules/sessionstore/SessionStore.jsm:281
undoCloseTab chrome://browser/content/browser.js:7685
oncommand chrome://browser/content/browser.xul:1
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
DebuggeeWouldRun: debuggee `resource://devtools/shared/base-loader.js:362' would run builtin-modules.js:214:11
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
Failed to create tab tabbrowser.js:2538
browser.webProgress is null tabbrowser.js:2112
TypeError: browser.webProgress is null
tabbrowser.js:2112:5
NS_ERROR_UNEXPECTED: Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIScriptSecurityManager.getLoadContextCodebasePrincipal] browser-custom-element.js:1048
TypeError: aBrowser.webProgress is null
tabbrowser.js:1761:5
TypeError: tab.linkedBrowser.frameLoader.remoteTab is null
tabbrowser.js:4278:11
TypeError: initialBrowser.frameLoader.remoteTab is null
AsyncTabSwitcher.jsm:152:1