Collect active stylesheets and and apply asynchronously.

third_party/WebKit/Source/core/css/FontFaceSet.cpp

Index: third_party/WebKit/Source/core/css/FontFaceSet.cpp
diff --git a/third_party/WebKit/Source/core/css/FontFaceSet.cpp b/third_party/WebKit/Source/core/css/FontFaceSet.cpp
index c9c97e5123ae5480b0f53e118f227b5272301bc5..0be1e5fce9b81441a5415cbc8c0afca1ffc54465 100644
--- a/third_party/WebKit/Source/core/css/FontFaceSet.cpp
+++ b/third_party/WebKit/Source/core/css/FontFaceSet.cpp
@@ -310,9 +310,9 @@ bool FontFaceSet::hasForBinding(ScriptState*,
 
 const HeapListHashSet<Member<FontFace>>& FontFaceSet::cssConnectedFontFaceList()
     const {
-  Document* d = document();
-  d->ensureStyleResolver();  // Flush pending style changes.
-  return d->styleEngine()
+  Document* document = this->document();
+  document->updateActiveStyle();
+  return document->styleEngine()
       .fontSelector()
       ->fontFaceCache()
       ->cssConnectedFontFaces();
@@ -467,6 +467,7 @@ bool FontFaceSet::resolveFontStyle(const String& fontString, Font& font) {
 
   style->font().update(style->font().getFontSelector());
 
+  document()->updateActiveStyle();
   document()->ensureStyleResolver().computeFont(style.get(), *parsedStyle);
 
   font = style->font();