This tests that an open XMLHttpRequest connection will call onreadystatechange correctly when data is sent over an open connection.
0 responseText: This is chunk number 0
1 responseText: This is chunk number 0This is chunk number 1
2 responseText: This is chunk number 0This is chunk number 1This is chunk number 2
3 responseText: This is chunk number 0This is chunk number 1This is chunk number 2This is chunk number 3
4 responseText: This is chunk number 0This is chunk number 1This is chunk number 2This is chunk number 3This is chunk number 4