Accept text input only if selection has focus.

third_party/WebKit/Source/core/editing/EditorKeyBindings.cpp

 /*
  * Copyright (C) 2006, 2007 Apple, Inc.  All rights reserved.
  * Copyright (C) 2012 Google, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 48 matching lines @@
 
   if (!Behavior().ShouldInsertCharacter(*evt) || !CanEdit())
     return false;
 
   const Element* const focused_element =
       frame_->GetDocument()->FocusedElement();
   if (!focused_element) {
     // We may lose focused element by |command.execute(evt)|.
     return false;
   }
-  if (!focused_element->ContainsIncludingHostElements(
-          *frame_->Selection()
-               .ComputeVisibleSelectionInDOMTreeDeprecated()
-               .Start()
-               .ComputeContainerNode())) {
-    // We should not insert text at selection start if selection doesn't have
-    // focus. See http://crbug.com/89026
+  // We should not insert text at selection start if selection doesn't have
+  // focus.
+  if (!frame_->Selection().SelectionHasFocus())
     return false;
-  }
 
   // Return true to prevent default action. e.g. Space key scroll.
   if (DispatchBeforeInputInsertText(evt->target()->ToNode(), key_event->text) !=
       DispatchEventResult::kNotCanceled)
     return true;
 
   return InsertText(key_event->text, evt);
 }
 
 void Editor::HandleKeyboardEvent(KeyboardEvent* evt) {
   // Give the embedder a chance to handle the keyboard event.
   if (Client().HandleKeyboardEvent(frame_) || HandleEditingKeyboardEvent(evt))
     evt->SetDefaultHandled();
 }
 
 }  // namespace blink