Implement select listbox using shadow DOM

Source/core/editing/TextIterator.cpp

Index: Source/core/editing/TextIterator.cpp
diff --git a/Source/core/editing/TextIterator.cpp b/Source/core/editing/TextIterator.cpp
index 45a5f213b3a52a91642d61b585c07bc17b29ca7a..f60a7138437db40b16ba4d5849d5a34cb6b2b8b6 100644
--- a/Source/core/editing/TextIterator.cpp
+++ b/Source/core/editing/TextIterator.cpp
@@ -891,6 +891,11 @@ static bool shouldEmitNewlinesBeforeAndAfterNode(Node& node)
             || node.hasTagName(ulTag));
     }
 
+    // Need to make an exception for option and optgroup, because we want to
+    // keep the legacy behavior before we added renderers to them.
+    if (isHTMLOptionElement(&node) || isHTMLOptGroupElement(&node))
+        return false;
+
     // Need to make an exception for table cells, because they are blocks, but we
     // want them tab-delimited rather than having newlines before and after.
     if (isTableCell(&node))