SSE2 truncating double-to-i.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index b68ad38970892491b039c28f589b2201263b3a2a..675771dd90e9c1201352f477924b4efa005851a7 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -50,6 +50,7 @@ class DoubleConstant: public AllStatic {
  public:
   static const double min_int;
   static const double one_half;
+  static const double minus_zero;
   static const double negative_infinity;
 };
 
@@ -552,6 +553,7 @@ class ExternalReference BASE_EMBEDDED {
   // Static variables containing common double constants.
   static ExternalReference address_of_min_int();
   static ExternalReference address_of_one_half();
+  static ExternalReference address_of_minus_zero();
   static ExternalReference address_of_negative_infinity();
 
   Address address() const {return reinterpret_cast<Address>(address_);}