Change test_designMode to check for empty string instead of br tag

[julianrkung]

test_designMode incorrectly checks that the innerHTML after an element_clear is a <br> tag. Instead, the innerHTML property should be an empty string according to the W3C spec here: element clear.

The clear should follow the "To clear a content editable element" subroutine, which states:

3. Set element’s innerHTML IDL attribute to an empty string.

Nowhere in the spec for element clear is the insertion of a <br> tag mentioned, so rather than accept both answers, to be spec compliant only an empty string should be accepted.

[whimboo]

I think that this looks fine. But @andreastt added that part, so Andreas if you could check that too, we can get this merged.

[julianrkung]

Any updates on this? Would liked this pushed through before I forget about it

[whimboo]

As mentioned in my last commit it looks fine, and as such I will give r+. If @andreastt doesn't respond soon, we should assume its fine and can be merged.

[julianrkung]

Would it be possible to merge it now that sufficient time has passed without response?

[whimboo]

Yes, I think we should finally get this merged. Thanks for pinging.

[whimboo]

As it turned out and further discussed on https://bugzilla.mozilla.org/show_bug.cgi?id=1573801, the PR should have not been merged. After the comment of @andreastt on that bug I checked the behavior of Firefox, Chrome, and Safari. All of them show a <br> tag for an empty content-editable element in the developer tools. So chromedriver might do a replacement here?

Could someone please help with a backout of this patch? Thanks

[whimboo]

@julianrkung Please feel free to file an issue for further discussion. This PR cannot be reopened.

[julianrkung]

I opened another PR that accepts both <br> and the empty string "". I wasn't able to reproduce the <br> tag showing for empty content-editable elements in Chrome, but was able to reproduce it in Firefox. I did not try to reproduce it in Safari.