responseText is still buggy on ie8

[jamie-pate]

Sometimes ie8 will not load xhr content. The fix for #1922 seems to cause an additional problem in ie8 because it checks for xhr.responseType, which unfortunately is set manually to the responseType passed in. This causes ie8 to use xhr.response instead of xhr.responseText (sometimes?)

This commit introduced the issue. 509ec74

[IgorMinar]

possible dupe of #4738?

[jamie-pate]

Yup. Your solution posted is the similar to mine