This tests viewport datagrid.
Nodes attached to dom:
a0
a1
a2
a3
a4
a5
a6
a7
a8
a9
a10
a11
a12
a13
a14
Testing removal of some nodes
Should be missing node 0, 1, 3, 5 from dom:
Nodes attached to dom:
a2
a4
a6
a7
a8
a9
a10
a11
a12
a13
a14
Testing adding of some nodes back
Should have nodes 0, 1, 3, 5 back in dom and previously added nodes removed:
Nodes attached to dom:
a0
a1
a2
a3
a4
a5
a6
a7
a8
a9
a10
a11
a12
a13
a14