Bug 1659457 - Do clone xml-pretty-printer's UA widget. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D87714

dom/base/ShadowRoot.cpp

@@ -50,7 +50,8 @@ ShadowRoot::ShadowRoot(Element* aElement, ShadowRootMode aMode,
     : DocumentFragment(std::move(aNodeInfo)),
       DocumentOrShadowRoot(this),
       mMode(aMode),
-      mIsUAWidget(false) {
+      mIsUAWidget(false),
+      mIsStaticUAWidget(false) {
   SetHost(aElement);
 
   // Nodes in a shadow tree should never store a value
@@ -95,7 +96,14 @@ JSObject* ShadowRoot::WrapNode(JSContext* aCx,
 }
 
 void ShadowRoot::CloneInternalDataFrom(ShadowRoot* aOther) {
-  MOZ_ASSERT(!aOther->IsUAWidget());
+  MOZ_ASSERT(aOther->ShouldStaticClone());
+
+  if (aOther->IsUAWidget()) {
+    SetIsUAWidget();
+  }
+  if (aOther->IsStaticUAWidget()) {
+    SetIsStaticUAWidget();
+  }
 
   size_t sheetCount = aOther->SheetCount();
   for (size_t i = 0; i < sheetCount; ++i) {

dom/base/ShadowRoot.h

@@ -105,6 +105,9 @@ class ShadowRoot final : public DocumentFragment,
   nsresult Bind();
 
  private:
+  bool IsStaticUAWidget() const { return mIsStaticUAWidget; }
+
+
   void InsertSheetIntoAuthorData(size_t aIndex, StyleSheet&,
                                  const nsTArray<RefPtr<StyleSheet>>&);
 
@@ -200,12 +203,24 @@ class ShadowRoot final : public DocumentFragment,
 
   bool IsUAWidget() const { return mIsUAWidget; }
 
+  // Whether we should clone this shadow root for printing. We usually don't
+  // clone UA widgets (because they're attached and setup on bind), but we need
+  // to clone "static" UA widgets, which don't.
+  bool ShouldStaticClone() const {
+    return !IsUAWidget() || IsStaticUAWidget();
+  }
+
   void SetIsUAWidget() {
     MOZ_ASSERT(!HasChildren());
     SetFlags(NODE_HAS_BEEN_IN_UA_WIDGET);
     mIsUAWidget = true;
   }
 
+  void SetIsStaticUAWidget() {
+    MOZ_ASSERT(IsUAWidget());
+    mIsStaticUAWidget = true;
+  }
+
   void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
 
   // nsIRadioGroupContainer
@@ -274,7 +289,10 @@ class ShadowRoot final : public DocumentFragment,
   // tree.
   nsTArray<const Element*> mParts;
 
-  bool mIsUAWidget;
+  bool mIsUAWidget : 1;
+  // Whether this shadow root is "static" and should be cloned for static
+  // documents.
+  bool mIsStaticUAWidget : 1;
 
   nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;
 };

dom/base/nsINode.cpp

@@ -3305,7 +3305,7 @@ already_AddRefed<nsINode> nsINode::CloneAndAdopt(
 
         // Clone the Shadow DOM
         ShadowRoot* originalShadowRoot = aNode->AsElement()->GetShadowRoot();
-        if (originalShadowRoot && !originalShadowRoot->IsUAWidget()) {
+        if (originalShadowRoot && originalShadowRoot->ShouldStaticClone()) {
           RefPtr<ShadowRoot> newShadowRoot =
               clone->AsElement()->AttachShadowWithoutNameChecks(
                   originalShadowRoot->Mode());

dom/xml/nsXMLPrettyPrinter.cpp

@@ -89,6 +89,7 @@ nsresult nsXMLPrettyPrinter::PrettyPrint(Document* aDocument,
   RefPtr<ShadowRoot> shadowRoot = rootElement->GetShadowRoot();
   MOZ_RELEASE_ASSERT(shadowRoot && shadowRoot->IsUAWidget(),
                      "There should be a UA Shadow Root here.");
+  shadowRoot->SetIsStaticUAWidget();
 
   // Append the document fragment to the shadow dom.
   shadowRoot->AppendChild(*resultFragment, err);

layout/base/tests/chrome/chrome.ini

@@ -27,6 +27,8 @@ support-files =
   printpreview_images_sw.html
   printpreview_images_sw_ref.html
   printpreview_images_sw.js
+  printpreview_prettyprint.xml
+  printpreview_prettyprint_ref.xhtml
   color_adjust.html
   color_adjust_ref.html
   test_document_adopted_styles.html

layout/base/tests/chrome/printpreview_helper.xhtml

@@ -636,6 +636,11 @@ async function runTest22() {
     exitprintpreview();
   }
 
+  requestAnimationFrame(() => setTimeout(runTest23));
+}
+
+async function runTest23() {
+  await compareFiles("printpreview_prettyprint.xml", "printpreview_prettyprint_ref.xhtml");
   finish();
 }
 

layout/base/tests/chrome/printpreview_prettyprint.xml

@@ -0,0 +1 @@
+<out>Here be sea hags</out>

layout/base/tests/chrome/printpreview_prettyprint_ref.xhtml

@@ -0,0 +1,3 @@
+<out><div id="top" xmlns="http://www.w3.org/1999/xhtml"><link href="chrome://global/content/xml/XMLPrettyPrint.css" type="text/css" rel="stylesheet"/><div id="header"><p>
+        This XML file does not appear to have any style information associated with it. The document tree is shown below.
+      </p></div><main id="tree" class="highlight"><div>&lt;<span class="start-tag">out</span>&gt;<span class="text">Here be sea hags</span>&lt;/<span class="end-tag">out</span>&gt;</div></main></div></out>