v0.28.1

• Reenable three-pane scrolling in Chrome 72 (#1922, #1921)
• A new version of the highlightjs pack supports syntax highlighting for
  SCSS. (#1906, #1907)
• Allow manually-specified links to source code, appearing as a small icon
  near the top of each element's page (#1913, #1454, #1892)
• Dartdoc can be used just to generate warnings by passing --no-generate-docs
  (#1909, #1537).
• Dartdoc's default CSS now more closely resembles dartlang.org, with some
  miscellaneous alignment tweaks, Roboto font, and use of :hover to highlight
  links (#1916, #1372)
• Viewport parameters for mobile now prevent "stuck page" syndrome (#1916,
  #1911). Overscroll is now permitted for mobile.
• Fix a problem where we don't render greater than symbols in the header
  for Chrome 72 (#1919, #1918)
• Dartdoc now remembers scroll positions for all three columns while
  navigating (#1917, #1288, #1372, #779, #1870)
• Update analyzer package to 0.35.0 and several internal test/coverage
  infrastructure fixes.