Have Document::markers() return a reference

Source/core/editing/SplitTextNodeCommand.cpp

Index: Source/core/editing/SplitTextNodeCommand.cpp
diff --git a/Source/core/editing/SplitTextNodeCommand.cpp b/Source/core/editing/SplitTextNodeCommand.cpp
index 34086598049204fe46d585254ed927ef8d6ab949..3979a738f400bd79d5c68e40b44a0bc9fc06a718 100644
--- a/Source/core/editing/SplitTextNodeCommand.cpp
+++ b/Source/core/editing/SplitTextNodeCommand.cpp
@@ -62,7 +62,7 @@ void SplitTextNodeCommand::doApply()
 
     m_text1 = Text::create(document(), prefixText);
     ASSERT(m_text1);
-    document().markers()->copyMarkers(m_text2.get(), 0, m_offset, m_text1.get(), 0);
+    document().markers().copyMarkers(m_text2.get(), 0, m_offset, m_text1.get(), 0);
 
     insertText1AndTrimText2();
 }
@@ -78,7 +78,7 @@ void SplitTextNodeCommand::doUnapply()
 
     m_text2->insertData(0, prefixText, ASSERT_NO_EXCEPTION, CharacterData::DeprecatedRecalcStyleImmediatlelyForEditing);
 
-    document().markers()->copyMarkers(m_text1.get(), 0, prefixText.length(), m_text2.get(), 0);
+    document().markers().copyMarkers(m_text1.get(), 0, prefixText.length(), m_text2.get(), 0);
     m_text1->remove(ASSERT_NO_EXCEPTION);
 }