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

Source/core/html/HTMLTextFormControlElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 261 matching lines @@
 
 void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextFieldSelectionDirection direction)
 {
     document().updateLayoutIgnorePendingStylesheets();
 
     if (!renderer() || !renderer()->isTextControl())
         return;
 
     end = max(end, 0);
     start = min(max(start, 0), end);
+    cacheSelection(start, end, direction);

[tkent, 2014/04/29 23:55:44]

What happens if |start| or |end| is larger than value().length()?

[harpreet.sk, 2014/04/30 14:36:27]

The browser will displays the caret at end of the text when value.length() is
less than |start| or |end|. I have added this case in layout test.

 
-    if (!hasVisibleTextArea(renderer(), innerTextElement())) {
-        cacheSelection(start, end, direction);
+    if (!hasVisibleTextArea(renderer(), innerTextElement()))
         return;
-    }
     VisiblePosition startPosition = visiblePositionForIndex(start);
     VisiblePosition endPosition;
     if (start == end)
         endPosition = startPosition;
     else
         endPosition = visiblePositionForIndex(end);
 
     // startPosition and endPosition can be null position for example when
     // "-webkit-user-select: none" style attribute is specified.
     if (startPosition.isNotNull() && endPosition.isNotNull()) {
@@ skipping 168 matching lines @@
 void HTMLTextFormControlElement::restoreCachedSelection()
 {
     setSelectionRange(m_cachedSelectionStart, m_cachedSelectionEnd, m_cachedSelectionDirection);
 }
 
 void HTMLTextFormControlElement::selectionChanged(bool userTriggered)
 {
     if (!renderer() || !isTextFormControl())
         return;
 
-    // selectionStart() or selectionEnd() will return cached selection when this node doesn't have focus
-    cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
-
     if (LocalFrame* frame = document().frame()) {
         if (frame->selection().isRange() && userTriggered)
             dispatchEvent(Event::createBubble(EventTypeNames::select));
     }
 }
 
 void HTMLTextFormControlElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == placeholderAttr) {
         updatePlaceholderVisibility(true);
@@ skipping 157 matching lines @@
 
     return "ltr";
 }
 
 HTMLElement* HTMLTextFormControlElement::innerTextElement() const
 {
     return toHTMLElement(userAgentShadowRoot()->getElementById(ShadowElementNames::innerEditor()));
 }
 
 } // namespace Webcore