Correctly re-collect active style for html imports.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 1032 matching lines @@
 void StyleEngine::initialViewportChanged() {
   if (m_viewportResolver)
     m_viewportResolver->initialViewportChanged();
 }
 
 void StyleEngine::viewportRulesChanged() {
   if (m_viewportResolver)
     m_viewportResolver->setNeedsCollectRules();
 }
 
-void StyleEngine::importRemoved() {
+void StyleEngine::htmlImportAddedOrRemoved() {
   if (document().importLoader()) {
-    document().importsController()->master()->styleEngine().importRemoved();
+    document()
+        .importsController()
+        ->master()
+        ->styleEngine()
+        .htmlImportAddedOrRemoved();
     return;
   }
 
   // When we remove an import link and re-insert it into the document, the
   // import Document and CSSStyleSheet pointers are persisted. That means the
   // comparison of active stylesheets is not able to figure out that the order
   // of the stylesheets have changed after insertion.
   //
+  // This is also the case when we import the same document twice where the
+  // last inserted document is inserted before the first one in dom order where
+  // the last would take precedence.
+  //
   // Fall back to re-add all sheets to the scoped resolver and recalculate style
-  // for the whole document if we remove an import in case it is re-inserted
-  // into the document. The assumption is that removing html imports is very
-  // rare.
+  // for the whole document when we remove or insert an import document.
   if (ScopedStyleResolver* resolver = document().scopedStyleResolver()) {
+    markDocumentDirty();
     resolver->setNeedsAppendAllSheets();
     document().setNeedsStyleRecalc(
         SubtreeStyleChange, StyleChangeReasonForTracing::create(
                                 StyleChangeReason::ActiveStylesheetsUpdate));
   }
 }
 
 PassRefPtr<ComputedStyle> StyleEngine::findSharedStyle(
     const ElementResolveContext& elementResolveContext) {
   DCHECK(m_resolver);
@@ skipping 152 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : m_injectedAuthorStyleSheets) {
     visitor->traceWrappers(sheet);
   }
   visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 }  // namespace blink