JavaScript Tetris runtime packaged for PLAYCHIVE

Upstream repository: https://github.com/jakesgordon/javascript-tetris
Pinned revision: e5c0c42f7dac0f3514a55eff656c6e22e95d68ed
Upstream game: https://jakesgordon.com/games/tetris/

JavaScript Tetris is licensed under MIT. The full upstream license is included
at JAVASCRIPT-TETRIS-MIT.txt. The corresponding source is available from the
upstream repository above; PLAYCHIVE's packaging script is
scripts/build-javascript-tetris-web.sh.

The runtime uses only the upstream HTML, JavaScript and local texture image. The
small PLAYCHIVE loader reads an autostart query flag and calls the upstream
play() function; it makes no network requests and preserves game behavior.