Use Shadow DOM to display fallback content for images

Source/core/editing/TextIterator.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov.
  *
  * 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 20 matching lines @@
 #include "core/HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/FirstLetterPseudoElement.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/editing/VisiblePosition.h"
 #include "core/editing/VisibleUnits.h"
 #include "core/editing/htmlediting.h"
 #include "core/frame/FrameView.h"
 #include "core/html/HTMLElement.h"
+#include "core/html/HTMLImageElement.h"
+#include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLTextFormControlElement.h"
 #include "core/rendering/InlineTextBox.h"
 #include "core/rendering/RenderImage.h"
 #include "core/rendering/RenderTableCell.h"
 #include "core/rendering/RenderTableRow.h"
 #include "core/rendering/RenderTextControl.h"
 #include "core/rendering/RenderTextFragment.h"
 #include "platform/fonts/Character.h"
 #include "platform/fonts/Font.h"
 #include "platform/text/TextBoundaries.h"
@@ skipping 412 matching lines @@
 
             // Handle the current node according to its type.
             if (m_iterationProgress < HandledNode) {
                 bool handledNode = false;
                 if (renderer->isText() && m_node->nodeType() == Node::TEXT_NODE) { // FIXME: What about CDATA_SECTION_NODE?
                     handledNode = handleTextNode();
                 } else if (renderer && (renderer->isImage() || renderer->isRenderPart()
                     || (m_node && m_node->isHTMLElement()
                     && (isHTMLFormControlElement(toHTMLElement(*m_node))
                     || isHTMLLegendElement(toHTMLElement(*m_node))
+                    || isHTMLImageElement(toElement(*m_node))
                     || isHTMLMeterElement(toHTMLElement(*m_node))
                     || isHTMLProgressElement(toHTMLElement(*m_node)))))) {
                     handledNode = handleReplacedElement();
                 } else {
                     handledNode = handleNonTextNode();
                 }
                 if (handledNode)
                     m_iterationProgress = HandledNode;
                 if (m_positionNode)
                     return;
@@ skipping 339 matching lines @@
         emitCharacter(',', m_node->parentNode(), m_node, 0, 1);
         return true;
     }
 
     m_positionNode = m_node->parentNode();
     m_positionOffsetBaseNode = m_node;
     m_positionStartOffset = 0;
     m_positionEndOffset = 1;
     m_singleCharacterBuffer = 0;
 
-    if (m_emitsImageAltText && renderer->isImage() && renderer->isRenderImage()) {
-        m_text = toRenderImage(renderer)->altText();
+    if (m_emitsImageAltText) {
+        m_text = toHTMLElement(m_node)->altText();
         if (!m_text.isEmpty()) {
             m_textLength = m_text.length();
             m_lastCharacter = m_text[m_textLength - 1];
             return true;
         }
     }
 
     m_textLength = 0;
     m_lastCharacter = 0;
 
@@ skipping 560 matching lines @@
     m_textLength = 0;
 
     while (m_node && !m_havePassedStartNode) {
         // Don't handle node if we start iterating at [node, 0].
         if (!m_handledNode && !(m_node == m_endNode && !m_endOffset)) {
             RenderObject* renderer = m_node->renderer();
             if (renderer && renderer->isText() && m_node->nodeType() == Node::TEXT_NODE) {
                 // FIXME: What about CDATA_SECTION_NODE?
                 if (renderer->style()->visibility() == VISIBLE && m_offset > 0)
                     m_handledNode = handleTextNode();
-            } else if (renderer && (renderer->isImage() || renderer->isRenderPart())) {
+            } else if (renderer && (isHTMLImageElement(toElement(*m_node)) || isHTMLInputElement(toElement(*m_node)) || renderer->isRenderPart())) {
                 if (renderer->style()->visibility() == VISIBLE && m_offset > 0)
                     m_handledNode = handleReplacedElement();
             } else {
                 m_handledNode = handleNonTextNode();
             }
             if (m_positionNode)
                 return;
         }
 
         if (!m_handledChildren && m_node->hasChildren()) {
@@ skipping 1005 matching lines @@
             resultEnd = collapseTo;
             return;
         }
     }
 
     CharacterIterator computeRangeIterator(inputStart, inputEnd, iteratorFlagsForFindPlainText);
     calculateCharacterSubrange(computeRangeIterator, matchStart, matchLength, resultStart, resultEnd);
 }
 
 }