src/vs/platform/keybinding/common/abstractKeybindingService.ts/KeybindingModifierSet/has
class KeybindingModifierSet:	has(modifier: KeybindingModifier) {
		switch (modifier) {
			case 'ctrl': return this._ctrlKey;
			case 'shift': return this._shiftKey;
			case 'alt': return this._altKey;
			case 'meta': return this._metaKey;
		}
	}