src/vs/editor/standalone/browser/standaloneThemeServiceImpl.ts/StandaloneTheme/getDefault
class StandaloneTheme:	private getDefault(colorId: ColorIdentifier): Color | undefined {
		let color = this.defaultColors[colorId];
		if (color) {
			return color;
		}
		color = colorRegistry.resolveDefaultColor(colorId, this);
		this.defaultColors[colorId] = color;
		return color;
	}