RFR: 8303217: Webview loaded webpage is not showing play, volume related buttons for embeded Audio/Video elements [v3]

[Jay Bhaskar]

> Issue: default html5 video element not showing media controls
> Details: Media control design has been refactored in the current Webkit Gtk port. The CSS id 
>                 and properties related to media buttons, and slider have been removed, due to which the 
>                 media style mediaControlsAdwaita.css values are not being applied.
> Solution: restored media control keywords and mapped to CSS keywords values.

Jay Bhaskar has updated the pull request incrementally with one additional commit since the last revision:

  Handle missing enuns in SSPrimitiveValueMappings.h

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1049/files
  - new: https://git.openjdk.org/jfx/pull/1049/files/d062933a..adf1f1be

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1049&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1049&range=01-02

  Stats: 77 lines in 2 files changed: 77 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1049.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1049/head:pull/1049

PR: https://git.openjdk.org/jfx/pull/1049