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

src/wasm/function-body-decoder.cc

Index: src/wasm/function-body-decoder.cc
diff --git a/src/wasm/function-body-decoder.cc b/src/wasm/function-body-decoder.cc
index 2d25f7c3ddec79a332a04fa9140ba63673293000..f8e87d05970339eaa75a8fd68c4d1c2ca7dbe538 100644
--- a/src/wasm/function-body-decoder.cc
+++ b/src/wasm/function-body-decoder.cc
@@ -1158,6 +1158,7 @@ class WasmFullDecoder : public WasmDecoder {
             len = DecodeLoadMem(kWasmF64, MachineType::Float64());
             break;
           case kExprS128LoadMem:
+            CHECK_PROTOTYPE_OPCODE(wasm_simd_prototype);
             len = DecodeLoadMem(kWasmS128, MachineType::Simd128());
             break;
           case kExprI32StoreMem8:
@@ -1188,6 +1189,7 @@ class WasmFullDecoder : public WasmDecoder {
             len = DecodeStoreMem(kWasmF64, MachineType::Float64());
             break;
           case kExprS128StoreMem:
+            CHECK_PROTOTYPE_OPCODE(wasm_simd_prototype);
             len = DecodeStoreMem(kWasmS128, MachineType::Simd128());
             break;
           case kExprGrowMemory: {