Load the browser-generated crash page as a synthetic response for the
URL that was active when WebContent exited. This keeps the session
history entry, response URL, and created Document aligned with the same
navigation URL, so reload targets the original page without creating a
local document for an HTTP(S) history entry.
Suppress history metadata updates from the generated page and declare
an inert rel=icon. Fallback favicon loading now follows the HTML
condition that no link with the icon keyword exists, which avoids the
credentialed /favicon.ico request from the crashed origin.
Previously, if search was disabled, entering non-URL text would just
silently drop the search query (and on Qt, we would reload the current
URL). We now detect that the query did not result in a navigation and
load an error page instead, which directs the user to enable search.
