Rename MathNatives_2atan to MathNatives_atan2.

runtime/lib/math.cc

Index: runtime/lib/math.cc
diff --git a/runtime/lib/math.cc b/runtime/lib/math.cc
index 08f6ee87f985d146e1313df2e900cc446accd9a7..851fdad6737186c8930a256d9146dc9b39f8b731 100644
--- a/runtime/lib/math.cc
+++ b/runtime/lib/math.cc
@@ -51,9 +51,7 @@ DEFINE_NATIVE_ENTRY(MathNatives_atan, 1) {
   arguments->SetReturn(Double::Handle(Double::New(atan(operand.value()))));
 }
 
-// It is not possible to call the native MathNatives_atan2. Somehow this leads
-// to a dynamic error "native function 'MathNatives_atan2' cannot be found".
-DEFINE_NATIVE_ENTRY(MathNatives_2atan, 2) {
+DEFINE_NATIVE_ENTRY(MathNatives_atan2, 2) {
   GET_NATIVE_ARGUMENT(Double, operand1, arguments->At(0));
   GET_NATIVE_ARGUMENT(Double, operand2, arguments->At(1));
   arguments->SetReturn(Double::Handle(Double::New(