Add a kSimd128 machine type for Turbofan.

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 b540aa9bb18c192565d84fed9c96ae853398da4e..f7a797c2d808dbe887fb087e57814214ca105b18 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -133,6 +133,7 @@ void InstructionSelector::VisitLoad(Node* node) {
     case MachineRepresentation::kWord64:
       opcode = kX64Movq;
       break;
+    case MachineRepresentation::kSimd128:  // Fall through.
     case MachineRepresentation::kNone:
       UNREACHABLE();
       return;
@@ -219,6 +220,7 @@ void InstructionSelector::VisitStore(Node* node) {
       case MachineRepresentation::kWord64:
         opcode = kX64Movq;
         break;
+      case MachineRepresentation::kSimd128:  // Fall through.
       case MachineRepresentation::kNone:
         UNREACHABLE();
         return;
@@ -264,8 +266,9 @@ void InstructionSelector::VisitCheckedLoad(Node* node) {
     case MachineRepresentation::kFloat64:
       opcode = kCheckedLoadFloat64;
       break;
-    case MachineRepresentation::kBit:
-    case MachineRepresentation::kTagged:
+    case MachineRepresentation::kBit:      // Fall through.
+    case MachineRepresentation::kSimd128:  // Fall through.
+    case MachineRepresentation::kTagged:   // Fall through.
     case MachineRepresentation::kNone:
       UNREACHABLE();
       return;
@@ -316,8 +319,9 @@ void InstructionSelector::VisitCheckedStore(Node* node) {
     case MachineRepresentation::kFloat64:
       opcode = kCheckedStoreFloat64;
       break;
-    case MachineRepresentation::kBit:
-    case MachineRepresentation::kTagged:
+    case MachineRepresentation::kBit:      // Fall through.
+    case MachineRepresentation::kSimd128:  // Fall through.
+    case MachineRepresentation::kTagged:   // Fall through.
     case MachineRepresentation::kNone:
       UNREACHABLE();
       return;