fontSelector should be reset when removing stylesheets which has @font-face rule.

Source/core/css/StyleSheetContents.h

Index: Source/core/css/StyleSheetContents.h
diff --git a/Source/core/css/StyleSheetContents.h b/Source/core/css/StyleSheetContents.h
index 586fdbef4670ead7c48cf9e4a2381469284f934d..77b1b763f3cc30f609c3e3737f9a9e3fae31d2f1 100644
--- a/Source/core/css/StyleSheetContents.h
+++ b/Source/core/css/StyleSheetContents.h
@@ -89,6 +89,9 @@ public:
     void setHasSyntacticallyValidCSSHeader(bool b) { m_hasSyntacticallyValidCSSHeader = b; }
     bool hasSyntacticallyValidCSSHeader() const { return m_hasSyntacticallyValidCSSHeader; }
 
+    void setHasFontFaceRule(bool b) { m_hasFontFaceRule = b; }
+    bool hasFontFaceRule() const { return m_hasFontFaceRule; }
+
     void parserAddNamespace(const AtomicString& prefix, const AtomicString& uri);
     void parserAppendRule(PassRefPtr<StyleRuleBase>);
     void parserSetEncodingFromCharsetRule(const String& encoding);
@@ -161,6 +164,7 @@ private:
     bool m_usesRemUnits : 1;
     bool m_isMutable : 1;
     bool m_isInMemoryCache : 1;
+    bool m_hasFontFaceRule : 1;
 
     CSSParserContext m_parserContext;