fix(ngAnimate): ensure that only string-based addClass/removeClass values are applied

[matsko]

Closes #12458

[petebacondarwin]

@matsko - looks good but I think the implementation could be DRYer with a helper:

function addRemoveClassesPostDigest(element, add, remove) {
  var data = postDigestQueue.get(element);
  var updated = false;
  var classVal;

  var updateData = function(classes, value) {
    var changed = false;
    if (classes) {
      classes = isString(classes) ? classes.split(' ') :
                isArray(classes) ? classes : [];
      forEach(classes, function(className) {
        if (className) {
          changed = true;
          data[className] = value;
        }
      });
    }
    return changed;
  };

  if (!data) {
    postDigestQueue.put(element, data = {});
    postDigestElements.push(element);
  }

  updated = updateData(add, true);
  updated = updated || updateData(remove, false);


  if (!updated || postDigestElements.length > 1) return;

  ...

[ThomasBurleson]

@matsko, @petebacondarwin - Love the DRY refactor! Question: no support for functions that return strings?

[matsko]

@petebacondarwin the code has been updated. Please double check and merge in.

[petebacondarwin]

LGTM

[petebacondarwin]

Landed. Thanks @matsko.
Although I did tweak the test because I felt that it was clearer to have two it clauses with no conditional logic than the they clause. Hope you don't mind!

[petebacondarwin]

Doh! I only changes one of the test. Sorry.

[matsko]

Thank you sir :)