[V8] Implement SIMD Boolean vector types to allow mask registers.

src/machine-type.cc

Index: src/machine-type.cc
diff --git a/src/machine-type.cc b/src/machine-type.cc
index 9289673bd7a0c1ae446937bfd3a307f78ff0990a..ba555dd36a8fb585950dced621d4081778e27746 100644
--- a/src/machine-type.cc
+++ b/src/machine-type.cc
@@ -32,6 +32,12 @@ const char* MachineReprToString(MachineRepresentation rep) {
       return "kRepFloat64";
     case MachineRepresentation::kSimd128:
       return "kRepSimd128";
+    case MachineRepresentation::kSimd1x4:
+      return "kRepSimd1x4";
+    case MachineRepresentation::kSimd1x8:
+      return "kRepSimd1x8";
+    case MachineRepresentation::kSimd1x16:
+      return "kRepSimd1x16";
     case MachineRepresentation::kTaggedSigned:
       return "kRepTaggedSigned";
     case MachineRepresentation::kTaggedPointer: