src/vs/editor/common/languages/supports/tokenization.ts/ThemeTrieElementRule/constructor
class ThemeTrieElementRule:	constructor(fontStyle: FontStyle, foreground: ColorId, background: ColorId) {
		this._fontStyle = fontStyle;
		this._foreground = foreground;
		this._background = background;
		this.metadata = (
			(this._fontStyle << MetadataConsts.FONT_STYLE_OFFSET)
			| (this._foreground << MetadataConsts.FOREGROUND_OFFSET)
			| (this._background << MetadataConsts.BACKGROUND_OFFSET)
		) >>> 0;
	}