Bug fix: StyledMarkupSerializer's m_lastClosed can be null

Source/core/editing/StyledMarkupSerializerTest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/editing/StyledMarkupSerializer.h"
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
@@ skipping 187 matching lines @@
 
 TEST_F(StyledMarkupSerializerTest, StyleDisplayNone)
 {
     const char* bodyContent = "<b>00<i style='display:none'>11</i>22</b>";
     setBodyContent(bodyContent);
     const char* expectedResult = "<b>0022</b>";
     EXPECT_EQ(expectedResult, serialize<EditingStrategy>());
     EXPECT_EQ(expectedResult, serialize<EditingInComposedTreeStrategy>());
 }
 
+TEST_F(StyledMarkupSerializerTest, StyleDisplayNoneAndNewLines)
+{
+    const char* bodyContent = "<div style='display:none'>11</div>\n\n";
+    setBodyContent(bodyContent);
+    EXPECT_EQ("", serialize<EditingStrategy>());
+    EXPECT_EQ("", serialize<EditingInComposedTreeStrategy>());
+}
+
 } // namespace blink