[wasm] JS API tests for `WebAssembly.validate`

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"
@@ skipping 306 matching lines @@
                                      &table->max_size);
             break;
           }
           case kExternalMemory: {
             // ===== Imported memory =========================================
             bool has_max = false;
             consume_resizable_limits("memory", "pages", kV8MaxWasmMemoryPages,
                                      &module->min_mem_pages, &has_max,
                                      kSpecMaxWasmMemoryPages,
                                      &module->max_mem_pages);
-            module->has_memory = true;
+            if (module->has_memory) {
+              error("At most one memory object is supported");
+            } else {
+              module->has_memory = true;
+            }
             break;
           }
           case kExternalGlobal: {
             // ===== Imported global =========================================
             import->index = static_cast<uint32_t>(module->globals.size());
             module->globals.push_back(
                 {kWasmStmt, false, WasmInitExpr(), 0, true, false});
             WasmGlobal* global = &module->globals.back();
             global->type = consume_value_type();
             global->mutability = consume_u8("mutability") != 0;
@@ skipping 889 matching lines @@
     table.push_back(std::move(func_asm_offsets));
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8