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 264 matching lines @@
     return setSelectionRange(start, end, direction);
 }
 
 void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextFieldSelectionDirection direction)
 {
     document().updateLayoutIgnorePendingStylesheets();
 
     if (!renderer() || !renderer()->isTextControl())
         return;
 
-    end = std::max(end, 0);
-    start = std::min(std::max(start, 0), end);
+    int textLength = innerEditorValue().length();
+    end = std::max(std::min(end, textLength), 0);
+    start = std::max(std::min(start, end), 0);
+    cacheSelection(start, end, direction);
+    bool isCaretSelection = start == end;
+    bool shouldSetSelection = document().focusedElement() == this || (!isCaretSelection && start < textLength);
 
-    if (!hasVisibleTextArea(renderer(), innerEditorElement())) {
-        cacheSelection(start, end, direction);
+    if (!hasVisibleTextArea(renderer(), innerEditorElement()))
         return;
-    }
+
+    LocalFrame* frame = document().frame();
+
+    if (!frame || !shouldSetSelection)
+        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()) {
         ASSERT(startPosition.deepEquivalent().deprecatedNode()->shadowHost() == this
             && endPosition.deepEquivalent().deprecatedNode()->shadowHost() == this);
     }
     VisibleSelection newSelection;
     if (direction == SelectionHasBackwardDirection)
         newSelection = VisibleSelection(endPosition, startPosition);
     else
         newSelection = VisibleSelection(startPosition, endPosition);
     newSelection.setIsDirectional(direction != SelectionHasNoDirection);
 
-    if (LocalFrame* frame = document().frame())
-        frame->selection().setSelection(newSelection);
+    frame->selection().setSelection(newSelection);
 }
 
 VisiblePosition HTMLTextFormControlElement::visiblePositionForIndex(int index) const
 {
     if (index <= 0)
         return VisiblePosition(firstPositionInNode(innerEditorElement()), DOWNSTREAM);
     RefPtrWillBeRawPtr<Range> range = Range::create(document());
     range->selectNodeContents(innerEditorElement(), ASSERT_NO_EXCEPTION);
     CharacterIterator it(range.get());
     it.advance(index - 1);
@@ skipping 146 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 (document().focusedElement() == this)
+        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) {
@@ skipping 161 matching lines @@
 
     return "ltr";
 }
 
 HTMLElement* HTMLTextFormControlElement::innerEditorElement() const
 {
     return toHTMLElement(userAgentShadowRoot()->getElementById(ShadowElementNames::innerEditor()));
 }
 
 } // namespace Webcore