Completed css_computed_style_compose functionality ,
and css_computed_absolute_* functions in the dispatch code , due to cyclic depdendency

  dispatch > properties > propget(computed and computed-absolute) + propset > dispatch
 breaked to
  dispatch + computed-absolute > properties > propget(computed) + propset
Merge branch 'master' of https://github.com/webconvforge/sri-delhi-rust-libcss