This commit fixes a race condition happening when clicking on the "Link
Tracker" menu of the website, when the website_preview client action's
iframe is not loaded yet.
That menu uses the iframe's contentWindow.location (taking it from the
website service), which was not set before the "load" event of the
iframe.
With this commit, the contentWindow is set at the website service level
when setting the pageDocument, as it can be taken from it
(document.defaultView), and the link tracker is displayed only when
there is a contentWindow at the website service level.
task-2687506
Part-of: odoo/odoo#94631
Younn Olivier
231a07a483