emitIAS for the couple of blend instructions.

src/assembler_ia32.h

Index: src/assembler_ia32.h
diff --git a/src/assembler_ia32.h b/src/assembler_ia32.h
index 676f4f62d464f97d86855b9edfb070716135b650..dc600a2de663203bf618ace62b53a302b7268c16 100644
--- a/src/assembler_ia32.h
+++ b/src/assembler_ia32.h
@@ -523,6 +523,11 @@ public:
   void andps(XmmRegister dst, const Address &src);
   void orps(XmmRegister dst, XmmRegister src);
 
+  void blendvps(Type Ty, XmmRegister dst, XmmRegister src);
+  void blendvps(Type Ty, XmmRegister dst, const Address &src);
+  void pblendvb(Type Ty, XmmRegister dst, XmmRegister src);
+  void pblendvb(Type Ty, XmmRegister dst, const Address &src);
+
   void cmpps(XmmRegister dst, XmmRegister src, CondX86::CmppsCond CmpCondition);
   void cmpps(XmmRegister dst, const Address &src,
              CondX86::CmppsCond CmpCondition);