[wasm] Gate SIMD load/store opcodes with the --wasm-simd-prototype flag.

test/mjsunit/wasm/wasm-constants.js

 // 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.
 
 // Flags: --expose-wasm
 
 function bytes() {
   var buffer = new ArrayBuffer(arguments.length);
   var view = new Uint8Array(buffer);
   for (var i = 0; i < arguments.length; i++) {
@@ skipping 297 matching lines @@
 let kExprF32ConvertF64 = 0xb6;
 let kExprF64SConvertI32 = 0xb7;
 let kExprF64UConvertI32 = 0xb8;
 let kExprF64SConvertI64 = 0xb9;
 let kExprF64UConvertI64 = 0xba;
 let kExprF64ConvertF32 = 0xbb;
 let kExprI32ReinterpretF32 = 0xbc;
 let kExprI64ReinterpretF64 = 0xbd;
 let kExprF32ReinterpretI32 = 0xbe;
 let kExprF64ReinterpretI64 = 0xbf;
+let kExprS128LoadMem = 0xc0;
 
 let kTrapUnreachable          = 0;
 let kTrapMemOutOfBounds       = 1;
 let kTrapDivByZero            = 2;
 let kTrapDivUnrepresentable   = 3;
 let kTrapRemByZero            = 4;
 let kTrapFloatUnrepresentable = 5;
 let kTrapFuncInvalid          = 6;
 let kTrapFuncSigMismatch      = 7;
 let kTrapInvalidIndex         = 8;
@@ skipping 35 matching lines @@
       eval(code);
     }
   } catch (e) {
     assertEquals('number', typeof e);
     assertEquals(value, e);
     // Success.
     return;
   }
   throw new MjsUnitAssertionError('Did not throw, expected: ' + value);
 }