ParserTests selser test generation: do not edit mw:Entity spans

* Noticed that edits were generating DOM with
  <span typeof="mw:Entity">askjfkdjsadfk38&lt;</span>
  which are invalid entities.

  Unsure if we want to test this scenario or not or if we
  expect clients to return valid entities in these spans.

Change-Id: I671a99a60d161ba1d2040ab9f41cec3f9f55d260
Merge "ParserTests selser test generation: do not edit mw:Entity spans"