VectorICs: Remove --vector-stores flag.

src/ic/x64/access-compiler-x64.cc

Index: src/ic/x64/access-compiler-x64.cc
diff --git a/src/ic/x64/access-compiler-x64.cc b/src/ic/x64/access-compiler-x64.cc
index 85b44ef47570dee57f59626ef619ad29618b5202..b8d50b3d2cdbdc12f116f398ca80f30d52a0bf0f 100644
--- a/src/ic/x64/access-compiler-x64.cc
+++ b/src/ic/x64/access-compiler-x64.cc
@@ -31,8 +31,6 @@ Register* PropertyAccessCompiler::store_calling_convention() {
   // receiver, name, scratch1, scratch2, scratch3.
   Register receiver = StoreDescriptor::ReceiverRegister();
   Register name = StoreDescriptor::NameRegister();
-  DCHECK(FLAG_vector_stores ||
-         rbx.is(StoreTransitionDescriptor::MapRegister()));
   static Register registers[] = {receiver, name, rbx, rdi, r8};
   return registers;
 }