Implement optional turbofan UnalignedLoad and UnalignedStore operators

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index dd99e89296c28ebb1ce17504f112fc467fd96a6e..20ce61a21432b340172e4b0175ba21cc512be48c 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -265,6 +265,11 @@ void InstructionSelector::VisitStore(Node* node) {
   }
 }
 
+// Architecture supports unaligned access, therefore VisitLoad is used instead
+void InstructionSelector::VisitUnalignedLoad(Node* node) { UNREACHABLE(); }
+
+// Architecture supports unaligned access, therefore VisitStore is used instead
+void InstructionSelector::VisitUnalignedStore(Node* node) { UNREACHABLE(); }
 
 void InstructionSelector::VisitCheckedLoad(Node* node) {
   CheckedLoadRepresentation load_rep = CheckedLoadRepresentationOf(node->op());