A bunch of changes to speed up math on ARM....

src/codegen.h

Index: src/codegen.h
===================================================================
--- src/codegen.h	(revision 2110)
+++ src/codegen.h	(working copy)
@@ -223,11 +223,13 @@
 
 class UnarySubStub : public CodeStub {
  public:
-  UnarySubStub() { }
+  explicit UnarySubStub(bool overwrite)
+      : overwrite_(overwrite) { }
 
  private:
+  bool overwrite_;
   Major MajorKey() { return UnarySub; }
-  int MinorKey() { return 0; }
+  int MinorKey() { return overwrite_ ? 1 : 0; }
   void Generate(MacroAssembler* masm);
 
   const char* GetName() { return "UnarySubStub"; }