message: optimize Tone.isObject
  this should be about 25% faster
  taken from
  custom perf test:
diff: @@ -32,7 +32,7 @@ export function isNumber(arg: any): arg is number {
  * Test if the given argument is an object literal (i.e. `{}`);
  */
  export function isObject(arg: any): arg is object {
  - return (Object.prototype.toString.call(arg) === "[object Object]" && arg.constructor === Object);
  + return arg != null && typeof arg === "object" && Array.isArray(arg) === false;
  }
  /**
  