Handle non-empty whitespace textContent in Tooltip trigger

[nwalters512]

If a Tooltip trigger has non-empty textContent that consists solely of whitespace, Bootstrap will remove the title but won't add an aria-label with the contents of title. Here's a reproduction of this: https://jsfiddle.net/nwalters512/7y8edzxr/7/. This is a poor experience for folks using screen readers, as they won't have any accessible label for the trigger.

This PR changes the JS to check the falseyness of textContent.trim() instead of textContent directly.

[hebertcisco]

It was really helpful to use the String.prototype.trim() method to handle white space, it's the right thing to do.

[GeoSot]

Thank you, @nwalters512 .
I am not sure is valid to auto-trim given strings, as it may be given on purpose (yes, of course, out of logic, as many other things I cannot understand myself)

As handy it may be, please try to add some tests to support your PR, and I would suggest making this change easy to applied everywhere. So probably, the best place is the TemplateFactory

[nwalters512]

@GeoSot I can try adding some tests! Re: your recommendation to make this change in TemplateFactory, it's not clear to me how that would work, as none of the existing code in _fixTitle() is touching that. It's also not clear to me how much of this is actually reusable - this "fix title" seems pretty specific to tooltips.

[nwalters512]

I added a test case in e2900e9. I verified that it failed before this change and now passes.

[GeoSot]

@nwalters51 I have understood your suggestion and the cause of the issue.
I am sorry for the misleading answer as my previous comment was out of topic

Many thanks for your help here