Remove duplicated test, add IE ignore

[sculpt0r]

What is the purpose of this pull request?

Fix failing test for IE

Does your PR contain necessary tests?

All patches that change the editor code must include tests. You can always read more
on PR testing,
how to set the testing environment and
how to create tests
in the official CKEditor documentation.

This PR contains

• Unit tests
• Manual tests

Did you follow the CKEditor 4 code style guide?

Your code should follow the guidelines from the CKEditor 4 code style guide which helps keep the entire codebase consistent.

• PR is consistent with the code style guide

What is the proposed changelog entry for this pull request?

Skip

What changes did you make?

Give an overview…
There were two tests for loading XML asynchronously.

The oldest one has IE ignore.

The newest one was introduced with PR for fix another bug (#1134 ).

To remove a duplicated test, and preserve bug fix history in code:

• I remove the older test
• I add the same IE ignore, as older test has

Which issues does your PR resolve?

Closes #4499

[Dumluregn]

LGTM! 🎉

Indeed the test added in #4339 was almost identical to the existing one. I've checked and on IE8 and IE9 those tests are executed normally and pass, so CKEDITOR.env.version > 9 is there for the reason.

[f1ames]

Rebased onto latest major.

[f1ames]

Interesting we didn't noticed it earlier 🤔 Makes sense to get rid of older test since they are both the same as mentioned 👍

Since @Dumluregn already reviewed it I merging it 👍