Simplify the "is integer" checks in CFFCompiler.encodeNumber

The `isNaN` check is obviously redundant, since `NaN` is the only value that isn't equal to itself; see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN#Examples

The `parseFloat`/`parseInt` comparison would make sense if the `value` ever contains a String, which however is never actually the case. Besides looking through the code, I've also run the entire test-suite locally with `assert(typeof value === "number", "encodeNumber");` added at the top of the method and there were no failures.

Hence we can simplify the "is integer" check a bit in the `CFFCompiler.encodeNumber` method.

src/core/cff_parser.js

@@ -1483,8 +1483,7 @@ var CFFCompiler = (function CFFCompilerClosure() {
       return output.data;
     },
     encodeNumber: function CFFCompiler_encodeNumber(value) {
-      if (parseFloat(value) === parseInt(value, 10) && !isNaN(value)) {
-        // isInt
+      if (Number.isInteger(value)) {
         return this.encodeInteger(value);
       }
       return this.encodeFloat(value);