Improve FastCloneShallowArray/ObjectStubs with VFP copying on ARM

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
===================================================================
--- src/arm/macro-assembler-arm.h	(revision 12826)
+++ src/arm/macro-assembler-arm.h	(working copy)
@@ -758,6 +758,15 @@
   // Copies a fixed number of fields of heap objects from src to dst.
   void CopyFields(Register dst, Register src, RegList temps, int field_count);
 
+  // Copy a fixed number of fields of from src to dst using NEON.
+  // A contiguous range of VFP registers is specified to hold temporary values;
+  // providing more registers will result in smaller code size and lower
+  // execution time. Both dst and src must be word aligned (so no tagged
+  // pointers allowed). On completion, dst and src will point to the end of the
+  // copied regions.
+  void VFPCopyFields(Register dst, Register src, int field_count,
+                     SwVfpRegister first, SwVfpRegister last);
+
   // Copies a number of bytes from src to dst. All registers are clobbered. On
   // exit src and dst will point to the place just after where the last byte was
   // read or written and length will be zero.