Blink does not respect input.selectionStart and input.selectionEnd for some cases

Source/core/html/forms/TextFieldInputType.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 142 matching lines @@
     RefPtrWillBeRawPtr<HTMLInputElement> input(element());
 
     // We don't ask InputType::setValue to dispatch events because
     // TextFieldInputType dispatches events different way from InputType.
     InputType::setValue(sanitizedValue, valueChanged, DispatchNoEvent);
 
     if (valueChanged)
         input->updateView();
 
     unsigned max = visibleValue().length();
-    if (input->focused())
-        input->setSelectionRange(max, max);
-    else
-        input->cacheSelectionInResponseToSetValue(max);
+    if (input->focused()) {
+        if (input->selectionStart() != input->selectionEnd())
+            input->setSelectionRange(input->selectionStart(), input->selectionEnd());
+        else
+            input->setSelectionRange(max, max);
+    } else {
+        input->setSelectionRange(input->selectionStart(), input->selectionEnd());

[yosin_UTC9, 2014/07/03 01:58:36]

Why do we need to set same value to input field selection?

It seems we should to same thing for TEXTAREA.

[harpreet.sk, 2014/07/04 13:50:27]

In case if input field is focused and selection is caret and we are setting
value then caret should so move to the end of text

+    }
 
     if (!valueChanged)
         return;
 
     switch (eventBehavior) {
     case DispatchChangeEvent:
         // If the user is still editing this field, dispatch an input event rather than a change event.
         // The change event will be dispatched when editing finishes.
         if (input->focused())
             input->dispatchFormControlInputEvent();
@@ skipping 377 matching lines @@
     return shouldSpinButtonRespondToMouseEvents() && element().focused();
 }
 
 void TextFieldInputType::spinButtonDidReleaseMouseCapture(SpinButtonElement::EventDispatch eventDispatch)
 {
     if (eventDispatch == SpinButtonElement::EventDispatchAllowed)
         element().dispatchFormControlChangeEvent();
 }
 
 } // namespace WebCore