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 a3069b3bec5203fa5c2aedc57b0791250d4fe3da..b8fddeb675f9a73d7d3fbc0c41f69aefcf35bbd5 100644
--- a/Source/core/editing/TextIterator.cpp
+++ b/Source/core/editing/TextIterator.cpp
@@ -900,6 +900,11 @@ 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))