am 4bd6c862: am 3556305e: Merge "docs: hide the "back to top" link when...

am 4bd6c862: am 3556305e: Merge "docs: hide the "back to top" link when there\'s no vertical scroll also use local variables for DOM objects (in a slow effort to eventually remove all non-essential global vars)" into eclair

Merge commit '4bd6c862'

* commit '4bd6c862':
  docs: hide the "back to top" link when there's no vertical scroll