Store a copy of generic font settings at CSSFontSelector.

Source/platform/fonts/GenericFontFamilySettings.cpp

Index: Source/platform/fonts/GenericFontFamilySettings.cpp
diff --git a/Source/platform/fonts/GenericFontFamilySettings.cpp b/Source/platform/fonts/GenericFontFamilySettings.cpp
index 57b2c5b7a27af9e69d8ba8e5b029cc1ccbe2a55a..7f436745e7a587254f99165157a888c6bfbddc04 100644
--- a/Source/platform/fonts/GenericFontFamilySettings.cpp
+++ b/Source/platform/fonts/GenericFontFamilySettings.cpp
@@ -33,6 +33,17 @@
 
 namespace WebCore {
 
+GenericFontFamilySettings::GenericFontFamilySettings(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)
+{
+}
+
 // 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)
 {