Only allow one shadowRoot.

sky/engine/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 443 matching lines @@
                     if (haveRenderer)
                         exitNode();
                     if (m_positionNode) {
                         m_iterationProgress = HandledChildren;
                         return;
                     }
                     next = m_node->nextSibling();
                 }
 
                 if (!next && !parentNode && m_shadowDepth > 0) {
-                    // 4. Reached the top of a shadow root. If it's created by author, then try to visit the next
-                    // sibling shadow root, if any.
+                    // 4. Reached the top of a shadow root.
                     ShadowRoot* shadowRoot = toShadowRoot(m_node);
-                    ShadowRoot* nextShadowRoot = shadowRoot->olderShadowRoot();
-                    if (nextShadowRoot) {
-                        m_fullyClippedStack.pop();
-                        m_node = nextShadowRoot;
-                        m_iterationProgress = HandledNone;
-                        // m_shadowDepth is unchanged since we exit from a shadow root and enter another.
-                        pushFullyClippedState(m_fullyClippedStack, m_node);
-                    } else {
-                        // We are the last shadow root; exit from here and go back to where we were.
-                        m_node = shadowRoot->host();
-                        m_iterationProgress = HandledAuthorShadowRoots;
-                        --m_shadowDepth;
-                        m_fullyClippedStack.pop();
-                    }
+                    m_node = shadowRoot->host();
+                    m_iterationProgress = HandledAuthorShadowRoots;
+                    --m_shadowDepth;
+                    m_fullyClippedStack.pop();
                     continue;
                 }
             }
             m_fullyClippedStack.pop();
         }
 
         // set the new current node
         m_node = next;
         if (m_node)
             pushFullyClippedState(m_fullyClippedStack, m_node);
@@ skipping 1402 matching lines @@
             resultEnd = collapseTo;
             return;
         }
     }
 
     CharacterIterator computeRangeIterator(inputStart, inputEnd, iteratorFlagsForFindPlainText);
     calculateCharacterSubrange(computeRangeIterator, matchStart, matchLength, resultStart, resultEnd);
 }
 
 }