LibWeb: Split the WebAssemblyInstance object logic into multiple files

Now that we're adding a constructor to it, let's split it up like the
rest of LibWeb does.

Userland/Libraries/LibWeb/WebAssembly/WebAssemblyInstanceObject.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Object.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibWasm/AbstractMachine/AbstractMachine.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/WebAssembly/WebAssemblyObject.h>
+
+namespace Web::Bindings {
+
+class WebAssemblyInstanceObject final : public JS::Object {
+    JS_OBJECT(WebAssemblyInstanceObject, Object);
+
+public:
+    explicit WebAssemblyInstanceObject(JS::GlobalObject&, size_t index);
+    virtual void initialize(JS::GlobalObject&) override;
+    virtual ~WebAssemblyInstanceObject() override = default;
+
+    size_t index() const { return m_index; }
+    Wasm::ModuleInstance& instance() const { return WebAssemblyObject::s_instantiated_modules.at(m_index); }
+    auto& cache() { return WebAssemblyObject::s_module_caches.at(m_index); }
+
+    void visit_edges(Visitor&) override;
+
+    friend class WebAssemblyInstancePrototype;
+
+private:
+    size_t m_index { 0 };
+    Object* m_exports_object { nullptr };
+};
+
+}