src/vs/base/browser/keyboardEvent.ts/StandardKeyboardEvent/_computeKeybinding
class StandardKeyboardEvent:	private _computeKeybinding(): number {
		let key = KeyCode.Unknown;
		if (this.keyCode !== KeyCode.Ctrl && this.keyCode !== KeyCode.Shift && this.keyCode !== KeyCode.Alt && this.keyCode !== KeyCode.Meta) {
			key = this.keyCode;
		}

		let result = 0;
		if (this.ctrlKey) {
			result |= ctrlKeyMod;
		}
		if (this.altKey) {
			result |= altKeyMod;
		}
		if (this.shiftKey) {
			result |= shiftKeyMod;
		}
		if (this.metaKey) {
			result |= metaKeyMod;
		}
		result |= key;

		return result;
	}