message: Fix date placement in activity feed item placeholder.
diff: <div class="-container">
  <div class="-item">
  <div class="-header">
  -
  + <div class="-header-content">
  <div class="-header-avatar" />
  - <div class="-header-content">
  <div class="-header-byline">
  <div class="-header-byline-name">
  <span class="-placeholder-text" style="width: 100px" />
  </div>
  </div>
  -
  - <div class="-byline-date">
  - <span class="-placeholder-small" style="width: 75px" />
  </div>
  + <div class="-header-meta">
  + <span class="-placeholder-small" style="width: 75px" />
  </div>
  </div>
  