X64 Win64: Reimplement fmod so that it works.

src/runtime.js

Index: src/runtime.js
diff --git a/src/runtime.js b/src/runtime.js
index 789bfdb77fcd8b8fee2d37eaf4c8fa7b1a3b2bb3..6d06803434297f0f6248cdab75f5d0ad513000d8 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -218,7 +218,7 @@ function DIV(y) {
 function MOD(y) {
   var x = IS_NUMBER(this) ? this : %ToNumber(this);
   if (!IS_NUMBER(y)) y = %ToNumber(y);
-  return %NumberMod(x, y);
+  return %_NumberMod(x, y);
 }