Add DocumentTiming metrics for "time to first text paint"

Source/core/css/CSSFontSelector.cpp

 /*
  * Copyright (C) 2007, 2008, 2011 Apple Inc. All rights reserved.
  *           (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 110 matching lines @@
     if (genericFamilyName == FontFamilyNames::webkit_monospace)
         return settings.fixed(script);
     if (genericFamilyName == FontFamilyNames::webkit_pictograph)
         return settings.pictograph(script);
     if (genericFamilyName == FontFamilyNames::webkit_standard)
         return settings.standard(script);
 #endif
     return emptyAtom;
 }
 
+void CSSFontSelector::reportFirstNonBlankText(bool isCustomFont)
+{
+    if (isCustomFont)
+        m_document->markFirstCustomFontText();
+    m_document->markFirstNonBlankText();
+}
+
 PassRefPtr<FontData> CSSFontSelector::getFontData(const FontDescription& fontDescription, const AtomicString& familyName)
 {
     if (CSSSegmentedFontFace* face = m_fontFaceCache.get(fontDescription, familyName))
         return face->getFontData(fontDescription);
 
     // Try to return the correct font based off our settings, in case we were handed the generic font family name.
     AtomicString settingsFamilyName = familyNameFromSettings(m_genericFontFamilySettings, fontDescription, familyName);
     if (settingsFamilyName.isEmpty())
         return nullptr;
 
@@ skipping 38 matching lines @@
 #if ENABLE(OILPAN)
     visitor->trace(m_document);
     visitor->trace(m_fontFaceCache);
     visitor->trace(m_clients);
     visitor->trace(m_fontLoader);
 #endif
     FontSelector::trace(visitor);
 }
 
 }