Bug 1597154 - pt 3. Flip documentchannel whitelist to blacklist r=mattwoodrow

This fixes 1597154 because the lists of URIs here and in nsDocShell now
match.

Note that they don't exactly match, there's an exception for about:newtab
which we'll fix in a follow-up bug.

Differential Revision: https://phabricator.services.mozilla.com/D69136

docshell/base/nsDocShell.cpp

@@ -9355,6 +9355,8 @@ static bool IsConsideredSameOriginForUIR(nsIPrincipal* aTriggeringPrincipal,
   return NS_OK;
 }
 
+// Changes here should also be made in
+// E10SUtils.documentChannelPermittedForURI().
 static bool SchemeUsesDocChannel(nsIURI* aURI) {
   if (SchemeIsJavascript(aURI) || NS_IsAboutBlank(aURI)) {
     return false;