src/vs/editor/common/config/editorOptions.ts/EditorFontVariations/validate
class EditorFontVariations:	public validate(input: any): string {
		if (typeof input === 'undefined') {
			return this.defaultValue;
		}
		if (typeof input === 'string') {
			if (input === 'false') {
				return EditorFontVariations.OFF;
			}
			if (input === 'true') {
				return EditorFontVariations.TRANSLATE;
			}
			return input;
		}
		if (Boolean(input)) {
			return EditorFontVariations.TRANSLATE;
		}
		return EditorFontVariations.OFF;
	}