Use removeFontFace to avoid resetting fontSelector.

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index 01609cef72dfe1f672f2fcbbfee63fd30f384544..75eae601f450967ab659ce35f14b083c135196e0 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -535,26 +535,35 @@ StyleResolverChange StyleEngine::resolverChanged(RecalcStyleTime time, StyleReso
     return change;
 }
 
-void StyleEngine::resetFontSelector()
+void StyleEngine::clearFontCache()
+{
+    // We should not recreate FontSelector. Instead, clear fontFaceCache.
+    if (m_fontSelector)
+        m_fontSelector->fontFaceCache()->clear();
+    if (m_resolver)
+        m_resolver->invalidateMatchedPropertiesCache();
+}
+
+void StyleEngine::updateGenericFontFamilySettings()

[dglazkov, 2014/01/29 05:11:50]

Why do we need a separate function for this? When is this called?

[tasak, 2014/01/29 10:13:43]

The updateGenericFontFamilySettings will be invoked from WebSettings or
InternalSettings.

clearFontCache will be invoked from updateActiveStyleSheets when we update some
stylesheets which contains @font-face rule.

 {
     if (!m_fontSelector)
         return;
 
-    m_fontSelector->clearDocument();
-    if (m_resolver) {
-        m_fontSelector->unregisterForInvalidationCallbacks(m_resolver.get());
+    m_fontSelector->updateGenericFontFamilySettings(m_document);
+    if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
-    }
+}
 
-    // If the document has been already detached, we don't need to recreate
-    // CSSFontSelector.
-    if (m_document.isActive()) {
-        m_fontSelector = CSSFontSelector::create(&m_document);
-        if (m_resolver)
-            m_fontSelector->registerForInvalidationCallbacks(m_resolver.get());
-    } else {
-        m_fontSelector = 0;
-    }
+void StyleEngine::removeFontFaceRules(const Vector<const StyleRuleFontFace*>& fontFaceRules)
+{
+    if (!m_fontSelector)
+        return;
+
+    CSSSegmentedFontFaceCache* cache = m_fontSelector->fontFaceCache();
+    for (unsigned i = 0; i < fontFaceRules.size(); ++i)
+        cache->remove(fontFaceRules[i]);
+    if (m_resolver)
+        m_resolver->invalidateMatchedPropertiesCache();
 }
 
 void StyleEngine::markTreeScopeDirty(TreeScope& scope)