Delete unused code in console.js (#20860)

Summary:
The isPrimitive method in [console.js](https://github.com/facebook/react-native/blob/5c2720b089dd0fb277771b0ac8b0e7788c493e5d/Libraries/polyfills/console.js#L364) is unused. It should be deleted.
Pull Request resolved: #20860

Differential Revision: D13396715

Pulled By: cpojer

fbshipit-source-id: ddfd828086106c997dcc77f5eae67adb6a0c1dfa

Libraries/polyfills/console.js

@@ -361,17 +361,6 @@ const inspect = (function() {
     return typeof arg === 'function';
   }
 
-  function isPrimitive(arg) {
-    return (
-      arg === null ||
-      typeof arg === 'boolean' ||
-      typeof arg === 'number' ||
-      typeof arg === 'string' ||
-      typeof arg === 'symbol' || // ES6 symbol
-      typeof arg === 'undefined'
-    );
-  }
-
   function objectToString(o) {
     return Object.prototype.toString.call(o);
   }