Make sure end position of selection to delete editable

Source/core/editing/DeleteSelectionCommand.cpp

Index: Source/core/editing/DeleteSelectionCommand.cpp
diff --git a/Source/core/editing/DeleteSelectionCommand.cpp b/Source/core/editing/DeleteSelectionCommand.cpp
index 7b886c7b906e021ee6878f1542062a7f14ae1e41..6e8690f5d57b1668596292107cb5eb7ee970db2a 100644
--- a/Source/core/editing/DeleteSelectionCommand.cpp
+++ b/Source/core/editing/DeleteSelectionCommand.cpp
@@ -164,6 +164,10 @@ void DeleteSelectionCommand::initializePositionData()
     Position start, end;
     initializeStartEnd(start, end);
 
+    ASSERT(isEditablePosition(start, ContentIsEditable, DoNotUpdateStyle));
+    if (!isEditablePosition(end, ContentIsEditable, DoNotUpdateStyle))
+        end = lastEditablePositionBeforePositionInRoot(end, highestEditableRoot(start)).deepEquivalent();
+
     m_upstreamStart = start.upstream();
     m_downstreamStart = start.downstream();
     m_upstreamEnd = end.upstream();