Implement 'tabstop' as an HTML attribute

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 193 matching lines @@
 
 void Element::clearElementFlag(ElementFlags mask)
 {
     if (!hasRareData())
         return;
     elementRareData()->clearElementFlag(mask);
 }
 
 void Element::clearTabIndexExplicitlyIfNeeded()
 {
-    if (hasRareData())
+    if (hasRareData()) {
         elementRareData()->clearTabIndexExplicitly();
+        // As tabindex is removed, unless there is an tabstop attribute,
+        // revert tabstop to default to match tabindex at this point (0).
+        if (!hasAttribute(tabstopAttr))

[tkent, 2015/03/31 06:16:32]

hasAttribute -> fastHasAttribute

[kochi, 2015/03/31 08:04:24]

Done.

+            setTabStopInternal(true);
+    }
 }
 
 void Element::setTabIndexExplicitly(short tabIndex)
 {
     ensureElementRareData().setTabIndexExplicitly(tabIndex);
+    if (!hasAttribute(tabstopAttr))

[tkent, 2015/03/31 06:16:32]

Ditto.

[kochi, 2015/03/31 08:04:24]

Done.

+        setTabStopInternal(tabIndex >= 0);
 }
 
 void Element::setTabIndex(int value)
 {
     setIntegralAttribute(tabindexAttr, value);
 }
 
 short Element::tabIndex() const
 {
     return hasRareData() ? elementRareData()->tabIndex() : 0;
@@ skipping 1854 matching lines @@
             clearTabIndexExplicitlyIfNeeded();
             if (treeScope().adjustedFocusedElement() == this) {
                 // We might want to call blur(), but it's dangerous to dispatch
                 // events here.
                 document().setNeedsFocusedElementCheck();
             }
         } else if (parseHTMLInteger(value, tabindex)) {
             // Clamp tabindex to the range of 'short' to match Firefox's behavior.
             setTabIndexExplicitly(max(static_cast<int>(std::numeric_limits<short>::min()), std::min(tabindex, static_cast<int>(std::numeric_limits<short>::max()))));
         }
+    } else if (RuntimeEnabledFeatures::tabStopAttributeEnabled() && name == tabstopAttr) {
+        if (!hasAttribute(tabstopAttr)) {
+            // tabstop attribute removed.
+            clearElementFlag(TabStopWasSetExplicitly);
+            setTabStopInternal(tabIndex() >= 0);
+        } else {
+            // Treat empty attribute as true.
+            if (equalIgnoringCase(value, "true") || equalIgnoringCase(value, "")) {
+                setTabStopInternal(true);
+                setElementFlag(TabStopWasSetExplicitly, true);
+            } else if (equalIgnoringCase(value, "false")) {
+                setTabStopInternal(false);
+                setElementFlag(TabStopWasSetExplicitly, true);
+            }

[tkent, 2015/03/31 06:16:32]

What should happen if a string other than "true" "" "false" is specified?


I'm asking "invalid value default" in
https://html.spec.whatwg.org/multipage/infrastructure.html#keywords-and-enume...
.

[kochi, 2015/03/31 08:04:24]

If tabstop is not either of "true", "", "false", it falls back to default state,
as if no tabstop is specified.  In the default state, tabStop value depends on
its tabIndex value (e.g. true on tabindex=0, false on tabindex=-1).

Therefore the case (none of "true" "" "false") the attribute is ignored.

Code to handle the case was missing, so added with layout test change.

+        }
     }
 }
 
 bool Element::parseAttributeName(QualifiedName& out, const AtomicString& namespaceURI, const AtomicString& qualifiedName, ExceptionState& exceptionState)
 {
     AtomicString prefix, localName;
     if (!Document::parseQualifiedName(qualifiedName, prefix, localName, exceptionState))
         return false;
     ASSERT(!exceptionState.hadException());
 
@@ skipping 222 matching lines @@
     return isFocusable() && tabIndex() >= 0;
 }
 
 bool Element::isMouseFocusable() const
 {
     return isFocusable();
 }
 
 bool Element::tabStop() const
 {
-    // Any element which never supports focus will always return false.
-    return supportsFocus() && (hasRareData() ? elementRareData()->tabStop() : true);
+    if (hasElementFlag(TabStopWasSetExplicitly))
+        return elementRareData()->tabStop();
+    return tabIndex() >= 0;
 }
 
 void Element::setTabStop(bool flag)
 {
+    // Reflect the value in the HTML attribute. Note that we cannot use setBooleanAttribute()
+    // because the tabstop attribute is an enumerated attribute.
+    // After tabstop attribute is set, the property value is modified accordingly.
+    setAttribute(tabstopAttr, flag ? "true" : "false");
+}
+
+void Element::setTabStopInternal(bool flag)
+{
     ensureElementRareData().setTabStop(flag);
     focusStateChanged();
 }
 
 void Element::dispatchFocusEvent(Element* oldFocusedElement, WebFocusType type)
 {
     RefPtrWillBeRawPtr<FocusEvent> event = FocusEvent::create(EventTypeNames::focus, false, false, document().domWindow(), 0, oldFocusedElement);
     EventDispatcher::dispatchEvent(*this, FocusEventDispatchMediator::create(event.release()));
 }
 
@@ skipping 1106 matching lines @@
 {
 #if ENABLE(OILPAN)
     if (hasRareData())
         visitor->trace(elementRareData());
     visitor->trace(m_elementData);
 #endif
     ContainerNode::trace(visitor);
 }
 
 } // namespace blink