Added addXSLStyleSheet and removeXSLStyleSheet to StyleEngine.

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 95ad29c10c4b9ba51d77e1d5a8396d3944139ce7..fceaab9afa1536587b0f9d86540d7b20811333c6 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -71,6 +71,7 @@ StyleEngine::StyleEngine(Document& document)
     // We don't need to create CSSFontSelector for imported document or
     // HTMLTemplateElement's document, because those documents have no frame.
     , m_fontSelector(document.frame() ? CSSFontSelector::create(&document) : nullptr)
+    , m_xslStyleSheet(0)
 {
 }
 
@@ -286,7 +287,7 @@ void StyleEngine::addStyleSheetCandidateNode(Node* node, bool createdByParser)
 
     TreeScope& treeScope = isHTMLStyleElement(*node) ? node->treeScope() : m_document;
     ASSERT(isHTMLStyleElement(node) || treeScope == m_document);
-
+    ASSERT(!isXSLStyleSheet(node));
     TreeScopeStyleSheetCollection* collection = ensureStyleSheetCollectionFor(treeScope);
     ASSERT(collection);
     collection->addStyleSheetCandidateNode(node, createdByParser);
@@ -304,6 +305,7 @@ void StyleEngine::removeStyleSheetCandidateNode(Node* node)
 void StyleEngine::removeStyleSheetCandidateNode(Node* node, ContainerNode* scopingNode, TreeScope& treeScope)
 {
     ASSERT(isHTMLStyleElement(node) || treeScope == m_document);
+    ASSERT(!isXSLStyleSheet(node));
 
     TreeScopeStyleSheetCollection* collection = styleSheetCollectionFor(treeScope);
     ASSERT(collection);
@@ -313,6 +315,37 @@ void StyleEngine::removeStyleSheetCandidateNode(Node* node, ContainerNode* scopi
     m_activeTreeScopes.remove(&treeScope);
 }
 
+void StyleEngine::addXSLStyleSheet(Node* node, bool createdByParser)

[esprehn, 2014/05/22 18:32:20]

This should just take a ProcessingInstruction*

[tasak, 2014/05/27 06:17:30]

Done.

+{
+    if (!node->inDocument())
+        return;
+
+    ASSERT(isXSLStyleSheet(node));
+    bool needToUpdate = false;
+    if (createdByParser || !m_xslStyleSheet) {
+        needToUpdate = !m_xslStyleSheet;
+    } else {
+        unsigned position = m_xslStyleSheet->compareDocumentPositionInternal(node, Node::TreatShadowTreesAsDisconnected);
+        needToUpdate = position & Node::DOCUMENT_POSITION_FOLLOWING;
+    }
+
+    if (!needToUpdate)
+        return;
+
+    markTreeScopeDirty(m_document);
+    m_xslStyleSheet = toProcessingInstruction(node);
+}
+
+void StyleEngine::removeXSLStyleSheet(Node* node)

[esprehn, 2014/05/22 18:32:20]

ditto

[tasak, 2014/05/27 06:17:30]

Done.

+{
+    ASSERT(isXSLStyleSheet(node));
+    if (m_xslStyleSheet != node)
+        return;
+
+    markTreeScopeDirty(m_document);
+    m_xslStyleSheet = 0;
+}
+
 void StyleEngine::modifiedStyleSheetCandidateNode(Node* node)
 {
     if (!node->inDocument())
@@ -488,6 +521,11 @@ bool StyleEngine::shouldClearResolver() const
     return !m_didCalculateResolver && !haveStylesheetsLoaded();
 }
 
+bool StyleEngine::shouldApplyXSLTransform() const
+{
+    return m_xslStyleSheet && RuntimeEnabledFeatures::xsltEnabled() && !m_document.transformSourceDocument();

[esprehn, 2014/05/22 18:32:20]

Early return on the runtime enabled feature.

if (RuntimeEnabledFeatures::xsltEnabled())
  return false;

[tasak, 2014/05/27 06:17:30]

Done.

+}
+
 StyleResolverChange StyleEngine::resolverChanged(RecalcStyleTime time, StyleResolverUpdateMode mode)
 {
     StyleResolverChange change;
@@ -505,6 +543,15 @@ StyleResolverChange StyleEngine::resolverChanged(RecalcStyleTime time, StyleReso
         return change;
     }
 
+    if (shouldApplyXSLTransform()) {
+        // Processing instruction (XML documents only).
+        // We don't support linking to embedded CSS stylesheets, see <https://bugs.webkit.org/show_bug.cgi?id=49281> for discussion.
+        // Don't apply XSL transforms to already transformed documents -- <rdar://problem/4132806>
+        if (!m_document.parsing() && !m_xslStyleSheet->isLoading())
+            m_document.applyXSLTransform(m_xslStyleSheet);
+        return change;
+    }
+
     m_didCalculateResolver = true;
     if (m_document.didLayoutWithPendingStylesheets() && !hasPendingSheets())
         change.setNeedsRepaint();