Set proper referrer for css resource fetching

Source/core/css/CSSFontFaceSrcValue.cpp

Index: Source/core/css/CSSFontFaceSrcValue.cpp
diff --git a/Source/core/css/CSSFontFaceSrcValue.cpp b/Source/core/css/CSSFontFaceSrcValue.cpp
index d54f0deefda13f9baba7b6c47a029033f0652d12..9ef8d5682482a7131f80474a4fb02cea5894e363 100644
--- a/Source/core/css/CSSFontFaceSrcValue.cpp
+++ b/Source/core/css/CSSFontFaceSrcValue.cpp
@@ -105,6 +105,9 @@ FontResource* CSSFontFaceSrcValue::fetch(Document* document)
         if (shouldSetCrossOriginAccessControl(request.url(), securityOrigin)) {
             request.setCrossOriginAccessControl(securityOrigin, DoNotAllowStoredCredentials);
         }
+        if (!m_referrer.isEmpty())

[abarth-chromium, 2014/04/17 17:44:58]

When would m_referrer be empty?  Can we change this to an ASSERT?

[bashi, 2014/04/18 10:16:59]

Looks like strippedForUseAsReferrer() could return an empty string so I think it
is safer not to make this an ASSERT?

+            request.mutableResourceRequest().setHTTPReferrer(Referrer(m_referrer, ReferrerPolicyDefault));
+
         m_fetched = document->fetcher()->fetchFont(request);
     }
     return m_fetched.get();