X64 Win64: Reimplement fmod so that it works.

src/runtime.h

Index: src/runtime.h
diff --git a/src/runtime.h b/src/runtime.h
index 279181d07e384134de91fc8922134ec18e900865..16ffc5dc412b5a6426779cc04a6a3d6751e8ce54 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -69,6 +69,7 @@ namespace internal {
   F(NewArgumentsFast, 3, 1) \
   F(LazyCompile, 1, 1) \
   F(SetNewFunctionAttributes, 1, 1) \
+  F(AllocateHeapNumber, 0, 1) \
   \
   /* Array join support */ \
   F(PushIfAbsent, 2, 1) \