Change text truncation logic to more closely follow panel state

Several related changes to text truncation:
* remove untruncate-on-click so untruncated text is selectable
  (untruncate will happen on click to the canvas are instead,
  to be implemented in a followup patch)
* simplify the truncate/untruncate logic to be wholly based on
  panel open/close state, and fix a bug which made panel state
  and text truncation state inconsistent when prev/next
  navigating while keeping the panel open.
* remove several variations on scrolling the panel in favor of
  using toggle + remove some other unused truncation-related code
* fix a minor unrelated style bug which made truncate/untruncate more
  jarring than it had to be when the title was short by making the title
  higher on panel open even though the text did not use the extra height
* align title ellipsis better
* make sure clicking on the truncated title works even if the click is
  between lines and so misses the inline box of the <span>

Change-Id: Ie0b3afb3833102b6a9812cb7fe2df78ec5eb8396
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/983
Merge "Change text truncation logic to more closely follow panel state"