Trace StyleEngine::clearResolver

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index ac5e5483b9738c51603dde1240db6929fcf893c5..8f61504461b5ddd1396365e116888792f32fd843 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -394,7 +394,7 @@ void StyleEngine::appendActiveAuthorStyleSheets()
 
 void StyleEngine::createResolver()
 {
-    TRACE_EVENT0("blink", "StyleEngine::createResolver");
+    TRACE_EVENT1("blink", "StyleEngine::createResolver", "frame", document().frame());
     // It is a programming error to attempt to resolve style on a Document
     // which is not in a frame. Code which hits this should have checked
     // Document::isActive() before calling into code which could get here.
@@ -425,7 +425,10 @@ void StyleEngine::clearResolver()
     for (TreeScope* treeScope : m_activeTreeScopes)
         treeScope->clearScopedStyleResolver();
 
-    m_resolver.clear();
+    if (m_resolver) {
+        TRACE_EVENT1("blink", "StyleEngine::clearResolver", "frame", document().frame());
+        m_resolver.clear();
+    }
 }
 
 void StyleEngine::clearMasterResolver()