Take 2 on "Fix ajax to always expect an Error object, per #10646."

We can't use jQuery.error to rethrow anymore since it constructs a new Error from its supposedly-string arg. Also, older IE stringifies Error objects into "[object Error]" so I've loosened the unit test criteria.

This reverts commit 586fb05919.

src/ajax.js

@@ -752,10 +752,10 @@ jQuery.extend({
 			} catch (e) {
 				// Propagate exception as error if not done
 				if ( state < 2 ) {
-					done( -1, e.message );
+					done( -1, e );
 				// Simply rethrow otherwise
 				} else {
-					jQuery.error( e.message );
+					throw e;
 				}
 			}
 		}