Revert of Remove SIMD.js from V8.

test/cctest/ast-types-fuzz.h

Index: test/cctest/ast-types-fuzz.h
diff --git a/test/cctest/ast-types-fuzz.h b/test/cctest/ast-types-fuzz.h
index c156ec5c75a423b9b3060ad7d4e851369222ed66..ba6286d54a3fabd3c4918e3eaa3a43b79ef2d396 100644
--- a/test/cctest/ast-types-fuzz.h
+++ b/test/cctest/ast-types-fuzz.h
@@ -116,7 +116,6 @@
     for (int i = 0; i < 30; ++i) {
       types.push_back(Fuzz());
     }
-    USE(isolate_);  // Currently unused.
   }
 
   Handle<i::Map> object_map;
@@ -288,6 +287,19 @@
         }
         return type;
       }
+      case 8: {  // simd
+        static const int num_simd_types =
+#define COUNT_SIMD_TYPE(NAME, Name, name, lane_count, lane_type) +1
+            SIMD128_TYPES(COUNT_SIMD_TYPE);
+#undef COUNT_SIMD_TYPE
+        AstType* (*simd_constructors[num_simd_types])(Isolate*, Zone*) = {
+#define COUNT_SIMD_TYPE(NAME, Name, name, lane_count, lane_type) &AstType::Name,
+            SIMD128_TYPES(COUNT_SIMD_TYPE)
+#undef COUNT_SIMD_TYPE
+        };
+        return simd_constructors[rng_->NextInt(num_simd_types)](isolate_,
+                                                                zone_);
+      }
       default: {  // union
         int n = rng_->NextInt(10);
         AstType* type = None;