src/vs/editor/common/languages/supports/tokenization.ts/ColorMap/getId
class ColorMap:	public getId(color: string | null): ColorId {
		if (color === null) {
			return 0;
		}
		const match = color.match(colorRegExp);
		if (!match) {
			throw new Error('Illegal value for token color: ' + color);
		}
		color = match[1].toUpperCase();
		let value = this._color2id.get(color);
		if (value) {
			return value;
		}
		value = ++this._lastColorId;
		this._color2id.set(color, value);
		this._id2color[value] = Color.fromHex('#' + color);
		return value;
	}