Adjustments to button graphics for media controls.

Adjustments to button graphics for media controls.
https://bugs.webkit.org/show_bug.cgi?id=143797.
<rdar://problem/20083708>

Reviewed by Dean Jackson.

These changes are visual in nature and mainly affect the buttons.
I've gotten rid of the text-shadow for all the buttons,
used plus-lighter blending mode and changed the button opacity to reflect the specs,
and made all the buttons turn opaque white when active.

* Modules/mediacontrols/mediaControlsApple.css:
(audio::-webkit-media-controls-panel button):
(audio::-webkit-media-controls-rewind-button):
(audio::-webkit-media-controls-play-button):
(audio::-webkit-media-controls-play-button.paused):
(video::-webkit-media-controls-volume-max-button):
(video::-webkit-media-controls-volume-slider):
(video::-webkit-media-controls-volume-min-button):
(audio::-webkit-media-controls-wireless-playback-picker-button):
(audio::-webkit-media-controls-toggle-closed-captions-button):
(audio::-webkit-media-controls-closed-captions-container li.selected:hover::before):
(audio::-webkit-media-controls-fullscreen-button):
(audio::-webkit-media-controls-fullscreen-button.exit):
(audio::-webkit-media-controls-status-display):
(audio::-webkit-media-controls-timeline):
(audio::-webkit-media-controls-time-remaining-display):
(video:-webkit-full-screen::-webkit-media-controls-volume-max-button):
(video:-webkit-full-screen::-webkit-media-controls-volume-min-button):
(video:-webkit-full-screen::-webkit-media-controls-play-button):
(video:-webkit-full-screen::-webkit-media-controls-play-button.paused):
(video:-webkit-full-screen::-webkit-media-controls-seek-back-button):
(video:-webkit-full-screen::-webkit-media-controls-seek-forward-button):
(video::-webkit-media-controls-volume-max-button:active):
(video::-webkit-media-controls-volume-min-button:active):
(audio::-webkit-media-controls-toggle-closed-captions-button:active):
(audio::-webkit-media-controls-rewind-button:active):
(audio::-webkit-media-controls-play-button:active):
(video:-webkit-full-screen::-webkit-media-controls-volume-max-button:active):
(video:-webkit-full-screen::-webkit-media-controls-volume-min-button:active):
(video:-webkit-full-screen::-webkit-media-controls-play-button:active):
(video:-webkit-full-screen::-webkit-media-controls-seek-back-button:active):
(video:-webkit-full-screen::-webkit-media-controls-seek-forward-button:active):
(audio::-webkit-media-controls-fullscreen-button:active):

Using the pseudo id itself here currently does not work, which is why we rely on the button.* selector for these.
(video:-webkit-full-screen::-webkit-media-controls-panel button.paused:active):
(audio::-webkit-media-controls-panel button.paused:active):
(audio::-webkit-media-controls-panel button.exit:active):

Draw volume slider knob as opaque white when active.
Adjust colors of timeline and volume sliders now that we are using plus-lighter blending.
* Modules/mediacontrols/mediaControlsApple.js:
(Controller):
(Controller.prototype.createControls):
(Controller.prototype.handleVolumeSliderMouseDown):
(Controller.prototype.handleVolumeSliderMouseUp):
(Controller.prototype.drawTimelineBackground):
(Controller.prototype.drawVolumeBackground):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@182900 268f45cc-cd09-0410-ab3c-d52691b4dbfc