[Reland] Allow headless TabSocket in isolated worlds & remove obsolete logic

headless/lib/renderer/devtools_isolated_world_ids.h

Index: headless/lib/renderer/devtools_isolated_world_ids.h
diff --git a/headless/lib/renderer/devtools_isolated_world_ids.h b/headless/lib/renderer/devtools_isolated_world_ids.h
new file mode 100644
index 0000000000000000000000000000000000000000..bb83d09f525c11fede85b3b346b9fcba7bd12799
--- /dev/null
+++ b/headless/lib/renderer/devtools_isolated_world_ids.h
@@ -0,0 +1,18 @@
+// 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 HEADLESS_LIB_RENDERER_DEVTOOLS_ISOLATED_WORLD_IDS_H_
+#define HEADLESS_LIB_RENDERER_DEVTOOLS_ISOLATED_WORLD_IDS_H_
+
+namespace headless {
+
+// Keep in sync with DOMWrapperWorld::WorldId.
+enum {
+  kDevToolsFirstIsolatedWorldId = (1 << 29) + 1,
+  kDevToolsLastIsolatedWorldId = kDevToolsFirstIsolatedWorldId + 100,
+};
+
+}  // namespace headless
+
+#endif  // HEADLESS_LIB_RENDERER_DEVTOOLS_ISOLATED_WORLD_IDS_H_