Don't do a smi check twice in the TO_INTEGER macro.

src/macros.py

Index: src/macros.py
===================================================================
--- src/macros.py	(revision 5316)
+++ src/macros.py	(working copy)
@@ -120,7 +120,7 @@
 
 # Inline macros. Use %IS_VAR to make sure arg is evaluated only once.
 macro NUMBER_IS_NAN(arg) = (!%_IsSmi(%IS_VAR(arg)) && !(arg == arg));
-macro TO_INTEGER(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : ToInteger(arg));
+macro TO_INTEGER(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : %NumberToInteger(ToNumber(arg)));
 macro TO_INTEGER_MAP_MINUS_ZERO(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : %NumberToIntegerMapMinusZero(ToNumber(arg)));
 macro TO_INT32(arg) = (%_IsSmi(%IS_VAR(arg)) ? arg : (arg >> 0));
 macro TO_UINT32(arg) = (arg >>> 0);