Force adding sheets and recalc for html import re-ordering.

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 1018 matching lines @@
 void StyleEngine::initialViewportChanged() {
   if (m_viewportResolver)
     m_viewportResolver->initialViewportChanged();
 }
 
 void StyleEngine::viewportRulesChanged() {
   if (m_viewportResolver)
     m_viewportResolver->setNeedsCollectRules();
 }
 
+void StyleEngine::importRemoved() {
+  if (document().importLoader()) {
+    document().importsController()->master()->styleEngine().importRemoved();
+    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.
+  //
+  // 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.
+  if (ScopedStyleResolver* resolver = document().scopedStyleResolver()) {
+    resolver->setNeedsAppendAllSheets();
+    document().setNeedsStyleRecalc(
+        SubtreeStyleChange, StyleChangeReasonForTracing::create(
+                                StyleChangeReason::ActiveStylesheetsUpdate));
+  }
+}
+
 PassRefPtr<ComputedStyle> StyleEngine::findSharedStyle(
     const ElementResolveContext& elementResolveContext) {
   DCHECK(m_resolver);
   return SharedStyleFinder(
              elementResolveContext, m_globalRuleSet.ruleFeatureSet(),
              m_globalRuleSet.siblingRuleSet(),
              m_globalRuleSet.uncommonAttributeRuleSet(), *m_resolver)
       .findSharedStyle();
 }
 namespace {
@@ skipping 19 matching lines @@
 }
 
 }  // namespace
 
 void StyleEngine::applyRuleSetChanges(
     TreeScope& treeScope,
     const ActiveStyleSheetVector& oldStyleSheets,
     const ActiveStyleSheetVector& newStyleSheets) {
   HeapVector<Member<RuleSet>> changedRuleSets;
 
+  ScopedStyleResolver* scopedResolver = treeScope.scopedStyleResolver();
+  bool appendAllSheets =
+      scopedResolver && scopedResolver->needsAppendAllSheets();
+
   ActiveSheetsChange change =
       compareActiveStyleSheets(oldStyleSheets, newStyleSheets, changedRuleSets);
-  if (change == NoActiveSheetsChanged)
+  if (change == NoActiveSheetsChanged && !appendAllSheets)
     return;
 
   // With rules added or removed, we need to re-aggregate rule meta data.
   m_globalRuleSet.markDirty();
 
   unsigned changedRuleFlags = getRuleSetFlags(changedRuleSets);
   bool fontsChanged = treeScope.rootNode().isDocumentNode() &&
                       (changedRuleFlags & FontFaceRules);
   unsigned appendStartIndex = 0;
 
   // We don't need to clear the font cache if new sheets are appended.
   if (fontsChanged && change == ActiveSheetsChanged)
     clearFontCache();
 
   // - If all sheets were removed, we remove the ScopedStyleResolver.
   // - If new sheets were appended to existing ones, start appending after the
   //   common prefix.
   // - For other diffs, reset author style and re-add all sheets for the
   //   TreeScope.
   if (treeScope.scopedStyleResolver()) {
     if (newStyleSheets.isEmpty())
       resetAuthorStyle(treeScope);
-    else if (change == ActiveSheetsAppended)
+    else if (change == ActiveSheetsAppended && !appendAllSheets)
       appendStartIndex = oldStyleSheets.size();
     else
       treeScope.scopedStyleResolver()->resetAuthorStyle();
   }
 
   if (!newStyleSheets.isEmpty()) {
     treeScope.ensureScopedStyleResolver().appendActiveStyleSheets(
         appendStartIndex, newStyleSheets);
   }
 
@@ skipping 43 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : m_injectedAuthorStyleSheets) {
     visitor->traceWrappers(sheet);
   }
   visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 }  // namespace blink