Support WholeWord in window.find()

Source/core/editing/iterators/CharacterIterator.cpp

Index: Source/core/editing/iterators/CharacterIterator.cpp
diff --git a/Source/core/editing/iterators/CharacterIterator.cpp b/Source/core/editing/iterators/CharacterIterator.cpp
index 9d5e55558487e6d80b2dc1c8336af2fcf4b2af37..87b26095c342440cdd5d4fcff826672ee3d537e0 100644
--- a/Source/core/editing/iterators/CharacterIterator.cpp
+++ b/Source/core/editing/iterators/CharacterIterator.cpp
@@ -475,7 +475,11 @@ inline bool SearchBuffer::isWordStartMatch(size_t start, size_t length) const
     size_t wordBreakSearchStart = start + length;
     while (wordBreakSearchStart > start)
         wordBreakSearchStart = findNextWordFromIndex(m_buffer.data(), m_buffer.size(), wordBreakSearchStart, false /* backwards */);
-    return wordBreakSearchStart == start;
+    if (wordBreakSearchStart != start)
+        return false;
+    if (m_options & WholeWord)
+        return static_cast<int>(start + length) == findWordEndBoundary(m_buffer.data(), m_buffer.size(), wordBreakSearchStart);
+    return true;
 }
 
 inline size_t SearchBuffer::search(size_t& start)