Making the scrollbar scrubbable.

- This change in behavior will remove the ability to scrub anywhere in the gutter to
  start fast-scrolling, but requires the user to touch near the scroll bar to start
  fast-scrolling.
- Also fixes issue with wonky scrollbar due to the fake section breaks

Change-Id: I34b08ac46ea93f7f4cad7ccde1048a388ee6a55d