less: refactor with .position-absolutely mixin
less: remove invalid styling
shellViews: set nested mediaViews to 100% height
shellViews: extend styling to nested media-views

most mediaView styling is not top-level specific and should apply to
nested mediaViews as well
shellViews: remove extraneous styling

no need for .value-bar-view styling given that styling is already set on
.progress-bar-view
videoLinkShell: set playerView bottom above slider
editorView: stylefix: remove excessive space