Error for call constructor from Number.prototype.anyMethod, and Keyword 'for' on IE8

[zhaohuihua]

1. Symbol.for can't work on the IE8, changed to Symbol['for']
2. Error for call constructor from Number.prototype.anyMethod

   // Expect to use Decimal.prototype.toFixed replace the original method
   (function() {
   var originalToFixed = Number.prototype.toFixed;
   Number.prototype.toFixed = function(decimal) {
       if (window.Decimal && Decimal.prototype.toFixed) { 
           return new Decimal(this).toFixed(decimal);
       } else {
           return originalToFixed(this, decimal);
       }
   };
   )();

   TestCode (2).toFixed(2); will be run to line 4340 thrown error '[DecimalError] Invalid argument: 2' because line 4290 test typeof v returned 'object' if (t === 'number') changed to if (t === 'number' || v instanceof Number)

[MikeMcl]

I don't see a need for
|| v instanceof Number when new Decimal(this) in your example could simply be replaced with new Decimal(+this) or new Decimal(Number(this)) or new Decimal(this.valueOf()) etc.

[MikeMcl]

I changed Symbol.for to Symbol['for'] in v10.3.0.

Thanks for your input.