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 0ee5357cc42b47e66e28d36b2801d4b02709247f..2e296b6320cf42ff13ce6116e7084e92f34a9103 100644
--- a/Source/core/editing/iterators/CharacterIterator.cpp
+++ b/Source/core/editing/iterators/CharacterIterator.cpp
@@ -473,7 +473,11 @@ 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)