This patch implements the following optimizations:
1. Adds element id to the 'FormHandler'' cache. This avoids the need to call 'findRootForField'.
2. Removes the 'isAutofillEnabled' check in 'receiveMessage'. This check is unnecessary because
those messages are only triggered if autofill is enabled.
3. Skips registering the form submission handler if the address fields do not contain 'street-address'.
This is because, for every country, we don’t save the address if 'street-address' is not present.
4. Passes 'fieldName' to 'showPopupIfEmpty', so there is no need to call 'getFormHandler' in the function.
Differential Revision: https://phabricator.services.mozilla.com/D225969
404327a0e4