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

Source/core/dom/TreeScopeStyleSheetCollection.h

Index: Source/core/dom/TreeScopeStyleSheetCollection.h
diff --git a/Source/core/dom/TreeScopeStyleSheetCollection.h b/Source/core/dom/TreeScopeStyleSheetCollection.h
index 8fd439e9485cc25aefa56c3a378604af0e500ef8..c5eebf545ae78c8f76ff5682178ad8476600b62a 100644
--- a/Source/core/dom/TreeScopeStyleSheetCollection.h
+++ b/Source/core/dom/TreeScopeStyleSheetCollection.h
@@ -89,6 +89,8 @@ private:
     static StyleResolverUpdateType compareStyleSheets(const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet>>& oldStyleSheets, const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet>>& newStylesheets, WillBeHeapVector<RawPtrWillBeMember<StyleSheetContents>>& addedSheets);
     bool activeLoadingStyleSheetLoaded(const WillBeHeapVector<RefPtrWillBeMember<CSSStyleSheet>>& newStyleSheets);
 
+    friend class TreeScopeStyleSheetCollectionTest;
+
 protected:
     RawPtrWillBeMember<TreeScope> m_treeScope;
     bool m_hadActiveLoadingStylesheet;