Return const by ref instead of const by Value in FetchRequestData::method

Source/modules/fetch/FetchRequestData.h

Index: Source/modules/fetch/FetchRequestData.h
diff --git a/Source/modules/fetch/FetchRequestData.h b/Source/modules/fetch/FetchRequestData.h
index f9accec1f42ac8aa7f2d6e46e241bb3c90a07d14..38697526f32f67b7d1f20ccf262719a1ea09b1e3 100644
--- a/Source/modules/fetch/FetchRequestData.h
+++ b/Source/modules/fetch/FetchRequestData.h
@@ -64,7 +64,7 @@ public:
     ~FetchRequestData();
 
     void setMethod(AtomicString method) { m_method = method; }
-    const AtomicString method() const { return m_method; }
+    const AtomicString& method() const { return m_method; }
     void setURL(const KURL& url) { m_url = url; }
     const KURL& url() const { return m_url; }
     bool unsafeRequestFlag() const { return m_unsafeRequestFlag; }