Using array index hash code for string-to-number conversion.

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
===================================================================
--- src/arm/macro-assembler-arm.h	(revision 5357)
+++ src/arm/macro-assembler-arm.h	(working copy)
@@ -475,6 +475,12 @@
   // occurred.
   void IllegalOperation(int num_arguments);
 
+  // Picks out an array index from the hash field.
+  // Register use:
+  //   hash - holds the index's hash. Clobbered.
+  //   index - holds the overwritten index on exit.
+  void IndexFromHash(Register hash, Register index);
+
   // Get the number of least significant bits from a register
   void GetLeastBitsFromSmi(Register dst, Register src, int num_least_bits);