Use removeFontFace to avoid resetting fontSelector.

Source/platform/fonts/GenericFontFamilySettings.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 26 matching lines @@
     : m_standardFontFamilyMap(other.m_standardFontFamilyMap)
     , m_serifFontFamilyMap(other.m_serifFontFamilyMap)
     , m_fixedFontFamilyMap(other.m_fixedFontFamilyMap)
     , m_sansSerifFontFamilyMap(other.m_sansSerifFontFamilyMap)
     , m_cursiveFontFamilyMap(other.m_cursiveFontFamilyMap)
     , m_fantasyFontFamilyMap(other.m_fantasyFontFamilyMap)
     , m_pictographFontFamilyMap(other.m_pictographFontFamilyMap)
 {
 }
 
+GenericFontFamilySettings& GenericFontFamilySettings::operator=(const GenericFontFamilySettings& other)
+{
+    m_standardFontFamilyMap = other.m_standardFontFamilyMap;
+    m_serifFontFamilyMap = other.m_serifFontFamilyMap;
+    m_fixedFontFamilyMap = other.m_fixedFontFamilyMap;
+    m_sansSerifFontFamilyMap = other.m_sansSerifFontFamilyMap;
+    m_cursiveFontFamilyMap = other.m_cursiveFontFamilyMap;
+    m_fantasyFontFamilyMap = other.m_fantasyFontFamilyMap;
+    m_pictographFontFamilyMap = other.m_pictographFontFamilyMap;
+    return *this;
+}
+
 // Sets the entry in the font map for the given script. If family is the empty string, removes the entry instead.
 void GenericFontFamilySettings::setGenericFontFamilyMap(ScriptFontFamilyMap& fontMap, const AtomicString& family, UScriptCode script)
 {
     ScriptFontFamilyMap::iterator it = fontMap.find(static_cast<int>(script));
     if (family.isEmpty()) {
         if (it == fontMap.end())
             return;
         fontMap.remove(it);
     } else if (it != fontMap.end() && it->value == family) {
         return;
@@ skipping 87 matching lines @@
     m_standardFontFamilyMap.clear();
     m_serifFontFamilyMap.clear();
     m_fixedFontFamilyMap.clear();
     m_sansSerifFontFamilyMap.clear();
     m_cursiveFontFamilyMap.clear();
     m_fantasyFontFamilyMap.clear();
     m_pictographFontFamilyMap.clear();
 }
 
 }