Implement new focusing steps for modal <dialog>.

Source/core/html/HTMLDialogElement.cpp

 /*
  * Copyright (C) 2012 Google 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 21 matching lines @@
 #include "core/dom/NodeTraversal.h"
 #include "core/html/HTMLFormControlElement.h"
 #include "core/frame/FrameView.h"
 #include "core/rendering/RenderBlock.h"
 #include "core/rendering/style/RenderStyle.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
-static void runAutofocus(HTMLDialogElement* dialog)
+// This function chooses the focused element when showModal() is invoked, as described in the spec for showModal().
+static void setFocusForModalDialog(HTMLDialogElement* dialog)
 {
+    Element* focusableDescendant = 0;
     Node* next = 0;
     for (Node* node = dialog->firstChild(); node; node = next) {
-        if (node->isElementNode() && toElement(node)->isFormControlElement()) {
+        if (node->hasTagName(dialogTag))
+            next = NodeTraversal::nextSkippingChildren(*node, dialog);
+        else
+            next = NodeTraversal::next(*node, dialog);
+
+        if (!node->isElementNode())
+            continue;
+        Element* element = toElement(node);
+        if (element->isFormControlElement()) {
             HTMLFormControlElement* control = toHTMLFormControlElement(node);
             if (control->isAutofocusable()) {
                 control->focus();
                 control->setAutofocused();
                 return;
             }
         }
-        if (node->hasTagName(dialogTag))
-            next = NodeTraversal::nextSkippingChildren(*node, dialog);
-        else
-            next = NodeTraversal::next(*node, dialog);
+        if (!focusableDescendant && element->isFocusable())
+            focusableDescendant = element;
     }
+
+    if (focusableDescendant) {
+        focusableDescendant->focus();
+        return;
+    }
+
+    if (dialog->isFocusable()) {
+        dialog->focus();
+        return;
+    }
+
+    dialog->document().setFocusedElement(0);
 }
 
 static void inertSubtreesChanged(Document& document)
 {
     // When a modal dialog opens or closes, nodes all over the accessibility
     // tree can change inertness which means they must be added or removed from
     // the tree. The most foolproof way is to clear the entire tree and rebuild
     // it, though a more clever way is probably possible.
     Document* topDocument = document.topDocument();
     topDocument->clearAXObjectCache();
@@ skipping 64 matching lines @@
         return;
     }
     if (!inDocument()) {
         exceptionState.throwDOMException(InvalidStateError, "The element is not in a Document.");
         return;
     }
 
     document().addToTopLayer(this);
     setBooleanAttribute(openAttr, true);
 
-    runAutofocus(this);
+    // Throw away the AX cache first, so the subsequent steps don't have a chance of queuing up
+    // AX events on objects that would be invalidated when the cache is thrown away.
+    inertSubtreesChanged(document());
+
     forceLayoutForCentering();
-    inertSubtreesChanged(document());
+    setFocusForModalDialog(this);
 }
 
 void HTMLDialogElement::setCentered(LayoutUnit centeredPosition)
 {
     ASSERT(m_centeringMode == Uninitialized);
     m_centeredPosition = centeredPosition;
     m_centeringMode = Centered;
 }
 
 void HTMLDialogElement::setNotCentered()
@@ skipping 23 matching lines @@
 }
 
 bool HTMLDialogElement::shouldBeReparentedUnderRenderView(const RenderStyle* style) const
 {
     if (style && style->position() == AbsolutePosition)
         return true;
     return Element::shouldBeReparentedUnderRenderView(style);
 }
 
 } // namespace WebCore