[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..06181c742e310ad1e17dd267bb9c8e4639259235 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::kSimdBool4:
+      return "kRepSimdBool4";
+    case MachineRepresentation::kSimdBool8:
+      return "kRepSimdBool8";
+    case MachineRepresentation::kSimdBool16:
+      return "kRepSimdBool16";
     case MachineRepresentation::kTaggedSigned:
       return "kRepTaggedSigned";
     case MachineRepresentation::kTaggedPointer: