The goal of this change is to avoid any false appearance
that we are implementing the proposed scrollIntoView() API [1],
while we clearly don't.

So, changes:

 - Rename scrollIntoView to scrollToView
   on both Anchor and Highlight
 - Stop returning promises at both methods

I also updated all the tests to reflect this change.

[1] http://dev.w3.org/csswg/cssom-view/#dom-element-scrollintoview