Provide an optional parameter to the cursor manager's target setter
methods to prevent scrolling, allowing the cursor to be programmatically
initialized without needlessly scrolling the page.
Because the ScrollBehavior.ALWAYS option was actually non-functional and
was neither tested nor used in the PG code, it has been removed from the
enum and JSDocs.
Bug: Issue 5273
Change-Id: Ia299dca1ca178a8a4d60b64932b1f291e11b79de