Implement Instance instances correctly; fix a few error cases

src/wasm/wasm-objects.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/wasm-objects.h"
 #include "src/utils.h"
 
 #include "src/debug/debug-interface.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-module.h"
@@ skipping 274 matching lines @@
           obj->GetInternalField(kCompiledModule))) {
     return false;
   }
 
   // All checks passed.
   return true;
 }
 
 Handle<WasmInstanceObject> WasmInstanceObject::New(
     Isolate* isolate, Handle<WasmCompiledModule> compiled_module) {
-  Handle<Map> map = isolate->factory()->NewMap(
-      JS_OBJECT_TYPE, JSObject::kHeaderSize + kFieldCount * kPointerSize);
+  Handle<JSFunction> instance_cons(
+      isolate->native_context()->wasm_instance_constructor());
+  Handle<JSObject> instance_object =
+      isolate->factory()->NewJSObject(instance_cons, TENURED);
+  Handle<Symbol> instance_sym(isolate->native_context()->wasm_instance_sym());
+  Object::SetProperty(instance_object, instance_sym, instance_object, STRICT)
+      .Check();
   Handle<WasmInstanceObject> instance(
-      reinterpret_cast<WasmInstanceObject*>(
-          *isolate->factory()->NewJSObjectFromMap(map, TENURED)),
-      isolate);
+      reinterpret_cast<WasmInstanceObject*>(*instance_object), isolate);
 
   instance->SetInternalField(kCompiledModule, *compiled_module);
   instance->SetInternalField(kMemoryObject, isolate->heap()->undefined_value());
   Handle<WasmInstanceWrapper> instance_wrapper =
       WasmInstanceWrapper::New(isolate, instance);
   instance->SetInternalField(kWasmMemInstanceWrapper, *instance_wrapper);
   return instance;
 }
 
 WasmInstanceObject* WasmExportedFunction::instance() {
@@ skipping 526 matching lines @@
       !array->get(kPreviousInstanceWrapper)->IsFixedArray())
     return false;
   return true;
 }
 
 void WasmInstanceWrapper::set_instance_object(Handle<JSObject> instance,
                                               Isolate* isolate) {
   Handle<WeakCell> cell = isolate->factory()->NewWeakCell(instance);
   set(kWrapperInstanceObject, *cell);
 }