Don't clear FontFaceCache if no @font-face were removed.

Source/core/dom/DocumentStyleSheetCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 79 matching lines @@
 {
     StyleSheetCollection collection;
     ActiveDocumentStyleSheetCollector collector(collection);
     collectStyleSheets(engine, collector);
 
     StyleSheetChange change;
     analyzeStyleSheetChange(updateMode, collection, change);
 
     if (change.styleResolverUpdateType == Reconstruct) {
         engine.clearMasterResolver();
-        // FIMXE: The following depends on whether StyleRuleFontFace was modified or not.
-        // No need to always-clear font cache.
-        engine.clearFontCache();
+        // TODO(rune@opera.com): The following depends on whether StyleRuleFontFace was modified or not.
+        // We should only remove modified/removed @font-face rules, or @font-face rules from removed
+        // stylesheets. We currently avoid clearing the font cache when we have had an analyzed update
+        // and no @font-face rules were removed, in which case requiresFullStyleRecalc will be false.
+        if (change.requiresFullStyleRecalc)
+            engine.clearFontCache();
     } else if (StyleResolver* styleResolver = engine.resolver()) {
         if (change.styleResolverUpdateType != Additive) {
             ASSERT(change.styleResolverUpdateType == Reset);
             styleResolver->resetAuthorStyle(treeScope());
             engine.removeFontFaceRules(change.fontFaceRulesToRemove);
             styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
             styleResolver->lazyAppendAuthorStyleSheets(0, collection.activeAuthorStyleSheets());
         } else {
             styleResolver->lazyAppendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), collection.activeAuthorStyleSheets());
         }
     }
     if (change.requiresFullStyleRecalc)
         document().setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::ActiveStylesheetsUpdate));
 
     collection.swap(*this);
 
     updateUsesRemUnits();
 }
 
 }