This reverts commit 8bcb268.

Since our version of Chromium is also pinned, a new ChromeDriver (that
drops support for our Chromium version) can cause random (and unrelated
to the corresponding changes) errors on CI.
This commit pins the version of ChromeDriver and it should now be
manually upgraded to a vrsion that is compatible with th currently used
Chromium version.

PR Close #20940

There seems to be some issue that causes Chrome/ChromeDriver to
unexpectedly reload during the aio e2e tests, causing flakes. It is not
clear what exactly is causing the reloading, but to the best of my
knowledge it is something inside Chrome or ChromeDriver.

Pinning Chrome to r494239 (between 62.0.3185.0 and 62.0.3186.0) fixes
the flakes.

Fixes #20159

Related to #21422.

PR Close #21641

…ri (#22077)

Both Firefox and Safari are vulnerable to XSS if we use an inert document
created via `document.implementation.createHTMLDocument()`.

Now we check for those vulnerabilities and then use a DOMParser or XHR
strategy if needed.

Further the platform-server has its own library for parsing HTML, so we
sniff for that (by checking whether DOMParser exists) and fall back to
the standard strategy.

Thanks to @cure53 for the heads up on this issue.