Removed superfluous custom style DCHECK.

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 140 matching lines @@
   }
 
   // There's no style to update so just calling recalcStyle means we're updated.
   ClearNeedsStyleRecalc();
 
   RecalcDescendantStyles(change);
   ClearChildNeedsStyleRecalc();
 }
 
 void ShadowRoot::RebuildLayoutTree(Text*& next_text_sibling) {
-  // ShadowRoot doesn't support custom callbacks.
-  DCHECK(!HasCustomStyleCallbacks());
-
   if (!NeedsReattachLayoutTree() && !ChildNeedsReattachLayoutTree()) {
     SkipRebuildLayoutTree(next_text_sibling);
     return;
   }
 
   StyleSharingDepthScope sharing_scope(*this);
 
   ClearNeedsReattachLayoutTree();
   RebuildChildrenLayoutTrees(next_text_sibling);
   ClearChildNeedsReattachLayoutTree();
@@ skipping 210 matching lines @@
       ostream << "ShadowRootType::Open";
       break;
     case ShadowRootType::kClosed:
       ostream << "ShadowRootType::Closed";
       break;
   }
   return ostream;
 }
 
 }  // namespace blink