[wasm] Fix and tighten memory validation

src/wasm/wasm-js.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/api-natives.h"
 #include "src/api.h"
 #include "src/asmjs/asm-js.h"
 #include "src/asmjs/asm-typer.h"
 #include "src/asmjs/asm-wasm-builder.h"
 #include "src/assert-scope.h"
@@ skipping 290 matching lines @@
                   "Argument 0 must be a WebAssembly.Module")) {
     return;
   }
 
   Local<Object> module_obj = Local<Object>::Cast(args[0]);
   i::Handle<i::WasmModuleObject> i_module_obj =
       i::Handle<i::WasmModuleObject>::cast(v8::Utils::OpenHandle(*module_obj));
 
   MaybeLocal<Value> instance =
       InstantiateModuleImpl(i_isolate, i_module_obj, args, &thrower);
-  if (instance.IsEmpty()) return;
+  if (instance.IsEmpty()) {
+    DCHECK(thrower.error());
+    return;
+  }
 
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(instance.ToLocalChecked());
 }
 
 void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   v8::Isolate* isolate = args.GetIsolate();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
 
   HandleScope scope(isolate);
@@ skipping 565 matching lines @@
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_memory_sym(), isolate);
   return HasBrand(value, symbol);
 }
 
 bool WasmJs::IsWasmTableObject(Isolate* isolate, Handle<Object> value) {
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_table_sym(), isolate);
   return HasBrand(value, symbol);
 }
 }  // namespace internal
 }  // namespace v8