Check StyleSheetIsLoading before clearing LinkStyle sheet.

third_party/WebKit/Source/core/html/LinkStyle.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/html/LinkStyle.h"
 
 #include "core/css/StyleSheetContents.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/LocalFrameClient.h"
 #include "core/frame/SubresourceIntegrity.h"
@@ skipping 384 matching lines @@
 
   if (title.IsEmpty() || !IsUnset() || owner_->IsAlternate())
     return;
 
   const KURL& href = owner_->GetNonEmptyURLAttribute(hrefAttr);
   if (href.IsValid() && !href.IsEmpty())
     GetDocument().GetStyleEngine().SetPreferredStylesheetSetNameIfNotSet(title);
 }
 
 void LinkStyle::OwnerRemoved() {
+  if (StyleSheetIsLoading())
+    RemovePendingSheet();
+
   if (sheet_)
     ClearSheet();
-
-  if (StyleSheetIsLoading())
-    RemovePendingSheet();
 }
 
 DEFINE_TRACE(LinkStyle) {
   visitor->Trace(sheet_);
   LinkResource::Trace(visitor);
   ResourceOwner<StyleSheetResource>::Trace(visitor);
 }
 
 }  // namespace blink