Remove tabStop feature

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 8a3c55dc5d609d6304bf5fcb54fc2baa967b7c1f..a570a858fd96fe6ea9eb68a6b1f8e116d024db06 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -199,20 +199,13 @@ void Element::clearElementFlag(ElementFlags 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 (!fastHasAttribute(tabstopAttr))
-            setTabStopInternal(true);
-    }
 }
 
 void Element::setTabIndexExplicitly(short tabIndex)
 {
     ensureElementRareData().setTabIndexExplicitly(tabIndex);
-    if (!fastHasAttribute(tabstopAttr))
-        setTabStopInternal(tabIndex >= 0);
 }
 
 void Element::setTabIndex(int value)
@@ -2059,27 +2052,6 @@ void Element::parseAttribute(const QualifiedName& name, const AtomicString& valu
             // 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) {
-        UseCounter::count(document(), UseCounter::TabStopAttribute);
-        if (!hasAttribute(tabstopAttr)) {
-            // tabstop attribute removed.
-            clearElementFlag(TabStopWasSetExplicitly);
-            setTabStopInternal(tabIndex() >= 0);
-        } else {
-            // Treat empty attribute as true.
-            if (equalIgnoringCase(value, "true") || equalIgnoringCase(value, "")) {
-                setElementFlag(TabStopWasSetExplicitly, true);
-                setTabStopInternal(true);
-            } else if (equalIgnoringCase(value, "false")) {
-                setElementFlag(TabStopWasSetExplicitly, true);
-                setTabStopInternal(false);
-            } else {
-                // When value is other than "true", "false", "", the value is ignored and
-                // falls back the default state.
-                clearElementFlag(TabStopWasSetExplicitly);
-                setTabStopInternal(tabIndex() >= 0);
-            }
-        }
     }
 }
 
@@ -2216,18 +2188,6 @@ void Element::focus(bool restorePreviousSelection, WebFocusType type)
     if (!isFocusable())
         return;
 
-    if (shadowRoot() && tabIndex() >= 0 && !tabStop()) {
-        if (containsIncludingShadowDOM(document().focusedElement()))
-            return;
-
-        // Slide the focus to its inner node.
-        Node* next = document().page()->focusController().findFocusableNode(WebFocusTypeForward, *this);
-        if (next && next->isElementNode() && containsIncludingShadowDOM(next)) {
-            toElement(next)->focus(false, WebFocusTypeForward);
-            return;
-        }
-    }
-
     RefPtrWillBeRawPtr<Node> protect(this);
     if (!document().page()->focusController().setFocusedElement(this, document().frame(), type))
         return;
@@ -2332,28 +2292,6 @@ bool Element::isMouseFocusable() const
     return isFocusable();
 }
 
-bool Element::tabStop() const
-{
-    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);
-    if (shadowRoot() && shadowRoot()->containsIncludingShadowDOM(document().focusedElement()))
-        setFocus(true);
-}
-
 bool Element::isFocusedElementInDocument() const
 {
     return this == document().focusedElement();