Collect media query results for non-matching stylesheets.

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index ebcc74e49126cf53e100eda190e22c2d36aa7e4f..81a37da9eb1c03386ddb0cfd0e2f5c546f5220e4 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -1099,6 +1099,9 @@ void StyleEngine::ApplyRuleSetChanges(
     return;
   }
 
+  if (changed_rule_sets.IsEmpty())
+    return;
+
   if (changed_rule_flags & kKeyframesRules)
     ScopedStyleResolver::KeyframesRulesAdded(tree_scope);