[js] Implement nqp::x using String.repeat.

Author: pmurias

src/vm/js/Operations.nqp

@@ -399,7 +399,7 @@ class QAST::OperationsJS {
     add_simple_op('time_i', $T_NUM, [], sub () {"Math.floor(new Date().getTime() / 1000)"}, :sideffects);
 
     add_simple_op('escape', $T_STR, [$T_STR]);
-    add_simple_op('x', $T_STR, [$T_STR, $T_INT]);
+    add_simple_op('x', $T_STR, [$T_STR, $T_INT], sub ($what, $times) {"$what.repeat($times)"});
 
     add_simple_op('getcomp', $T_OBJ, [$T_STR], :sideffects);
 

src/vm/js/nqp-runtime/core.js

@@ -49,13 +49,6 @@ op.escape = function(str) {
       .replace(/"/g, '\\"');
 };
 
-op.x = function(str, times) {
-  if (!times) return '';
-  var ret = str;
-  while (--times) ret += str;
-  return ret;
-};
-
 function radixHelper(radix, str, zpos, flags) {
   var lowercase = 'a-' + String.fromCharCode('a'.charCodeAt(0) + radix - 11);
   var uppercase = 'A-' + String.fromCharCode('A'.charCodeAt(0) + radix - 11);