LibWeb/IndexedDB: Prevent copying and moving of RequestList

RequestList cannot be copied or moved, because m_pending_request_queue
contains lambdas that store pointers to the original RequestList and
completion steps that we don't have a reference to.

Fixes a bunch of WPT regressions and imports the ones that work.

Tests/LibWeb/Text/input/wpt-import/IndexedDB/idbobjectstore-request-source.any.js

@@ -0,0 +1,39 @@
+// META: global=window,worker
+// META: title=IndexedDB: The source of requests made against object stores
+// META: script=resources/support.js
+
+// Spec: https://w3c.github.io/IndexedDB/#dom-idbrequest-source
+
+'use strict';
+
+[
+    store => store.put(0),
+    store => store.add(0),
+    store => store.delete(0),
+    store => store.clear(),
+
+    store => store.get(0),
+    store => store.getKey(0),
+    store => store.getAll(),
+    store => store.getAllKeys(),
+    store => store.count(),
+
+    store => store.openCursor(),
+    store => store.openKeyCursor()
+
+].forEach(
+        func => indexeddb_test(
+            (t, db) => {
+              db.createObjectStore('store', {autoIncrement: true});
+            },
+            (t, db) => {
+              const tx = db.transaction('store', 'readwrite');
+              const store = tx.objectStore('store');
+
+              assert_equals(
+                  func(store).source, store,
+                  `${func}.source should be the object store itself`);
+              t.done();
+            },
+            `The source of the request from ${
+                func} is the object store itself`));