[wasm] Simd128 types should not be available in asmjs modules.

src/wasm/module-decoder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/module-decoder.h"
 
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
+#include "src/flags.h"
 #include "src/macro-assembler.h"
 #include "src/objects.h"
 #include "src/v8.h"
 
 #include "src/wasm/decoder.h"
 
 namespace v8 {
 namespace internal {
 namespace wasm {
 
@@ skipping 906 matching lines @@
     switch (t) {
       case kLocalI32:
         return kAstI32;
       case kLocalI64:
         return kAstI64;
       case kLocalF32:
         return kAstF32;
       case kLocalF64:
         return kAstF64;
       case kLocalS128:
-        return kAstS128;
+        if (origin_ != kAsmJsOrigin && FLAG_wasm_simd_prototype) {
+          return kAstS128;
+        } else {
+          error(pc_ - 1, "invalid local type");
+          return kAstStmt;
+        }
       default:
         error(pc_ - 1, "invalid local type");
         return kAstStmt;
     }
   }
 
   // Parses a type entry, which is currently limited to functions only.
   FunctionSig* consume_sig() {
     if (!expect_u8("type form", kWasmFunctionTypeForm)) return nullptr;
     // parse parameter types
@@ skipping 169 matching lines @@
     decoder.consume_bytes(size);
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8