Use removeFontFace to avoid resetting fontSelector.

Source/core/dom/DocumentStyleSheetCollection.cpp

Index: Source/core/dom/DocumentStyleSheetCollection.cpp
diff --git a/Source/core/dom/DocumentStyleSheetCollection.cpp b/Source/core/dom/DocumentStyleSheetCollection.cpp
index 944213825715afa717a5b62a35c8e167f44aaf54..43743fd4f92759d5a16c369944befd10e50970bc 100644
--- a/Source/core/dom/DocumentStyleSheetCollection.cpp
+++ b/Source/core/dom/DocumentStyleSheetCollection.cpp
@@ -164,23 +164,19 @@ bool DocumentStyleSheetCollection::updateActiveStyleSheets(StyleEngine* engine,
 
     if (change.styleResolverUpdateType == Reconstruct) {
         engine->clearMasterResolver();
-        engine->resetFontSelector();

[ojan, 2013/12/18 00:20:02]

Is removing this line correct? In the reconstruct case, how do we know if font
face rules changed?

[tasak, 2013/12/18 05:12:23]

You are right.
If StyleFontFaceRule is updated by using CSSOMWrapper, we should reset
FontSelector.
And if a new style which has @font-face rule is inserted before another style
which also has @font-face rule, we should also reset FontSelector (because of
changing order of @font-face).

I added two layout tests to cover these cases.

     } else if (StyleResolver* styleResolver = engine->resolver()) {
         // FIXME: We might have already had styles in child treescope. In this case, we cannot use buildScopedStyleTreeInDocumentOrder.
         // Need to change "false" to some valid condition.
         styleResolver->setBuildScopedStyleTreeInDocumentOrder(false);
         if (change.styleResolverUpdateType != Additive) {
-            ASSERT(change.styleResolverUpdateType == Reset || change.styleResolverUpdateType == ResetStyleResolverAndFontSelector);
+            ASSERT(change.styleResolverUpdateType == Reset);
             resetAllRuleSetsInTreeScope(styleResolver);
-            if (change.styleResolverUpdateType == ResetStyleResolverAndFontSelector)
-                engine->resetFontSelector();
+            engine->removeFontFaceRules(change.fontFaceRulesToRemove);
             styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
             styleResolver->lazyAppendAuthorStyleSheets(0, collection.activeAuthorStyleSheets());
         } else {
             styleResolver->lazyAppendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), collection.activeAuthorStyleSheets());
         }
-    } else if (change.styleResolverUpdateType == ResetStyleResolverAndFontSelector) {
-        engine->resetFontSelector();
     }
     m_scopingNodesForStyleScoped.didRemoveScopingNodes();
     collection.swap(*this);