Revert of Allow headless TabSocket in isolated worlds & remove obsolete logic

third_party/WebKit/public/platform/WebIsolatedWorldIds.h

-// Copyright 2017 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef WebIsolatedWorldIds_h
-#define WebIsolatedWorldIds_h
-
-namespace blink {
-
-enum IsolatedWorldId {
-  // Embedder isolated worlds can use IDs in [1, 1<<29).
-  kEmbedderWorldIdLimit = (1 << 29),
-  kDocumentXMLTreeViewerWorldId,
-  kDevToolsFirstIsolatedWorldId,
-  kDevToolsLastIsolatedWorldId = kDevToolsFirstIsolatedWorldId + 100,
-  kIsolatedWorldIdLimit,
-};
-
-}  // namespace blink
-
-#endif  // WebIsolatedWorldIds_h