signon-ui fails to sign in to Google accounts

In KDE Plasma we are getting the following errors while signon-ui opens the Webkit window with the google login page:

browser-request.cpp 757 initializeField Couldn't find element: "input[name=Email]"
browser-request.cpp 757 initializeField Couldn't find element: "input[name=Passwd]"

which makes impossible to add a new google account using the Plasma account settings.

In KDE we ship kaccounts-providers that installs /etc/signon-ui/webkit-options.d/accounts.google.com.conf with the following content:

ViewportWidth = 480
ViewportHeight = 420
UsernameField = input[name="Email"]
PasswordField = input[name="Passwd"]
# Accept all https URLs, and add as exceptions those http only
# URLs which are used in some countries.
# See https://bugs.launchpad.net/bugs/1074733
AllowedUrls = (https://.*|http://[^/]*google\\.[^.]+/accounts/.*)

Has Google changed the HTML of the login page? Do we need to change UsernameField/PasswordField from the KDE side?