Bad value cleartype for attribute http-equiv on element meta.

Let's follow what core does #1717090: Remove the http-equiv="cleartype" meta tag even though that's been stalled for a month. Patch will have to be rerolled against dev when the time comes. Thanks, Adam!

We've decided to remove that metatag for Drupal 8 because we won't be supporting those old mobile Windows phones.

But I think we should support them on Drupal 7. Opinions?

Didn't mean to move it to the new branch.

We have still validation errors on this meta tag in W3C Validator. So even if it's now removed from D8, there should be a soltion in the D7 zen theme.
I like the solution of @acbramley and the patch works fine in branch 7.x-5.x-dev. This can be committed in my opinion.

There is a patch here.

I think the wrapping conditional comment is silly, but I'll add it to 7.x-5.x since I'm removing the whole metatag from 6.x.