From 921224f8f497e439fb55a8b15ca2c3f5bf38237c Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Tue, 22 Nov 2016 22:41:51 -0500
Subject: [PATCH] Bug 1319255 part 3.  Don't create special elements for
 <shadow> and <content> unless webcomponents are enabled.  r=wchen

---
 dom/base/nsDocument.cpp         | 25 +++++++++++++++++++++++--
 dom/base/nsDocument.h           |  6 ++++++
 dom/html/HTMLContentElement.cpp | 23 ++++++++++++++++++++++-
 dom/html/HTMLShadowElement.cpp  | 23 ++++++++++++++++++++++-
 4 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 5bb20c75ddd1..80aaded37ae1 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -5731,7 +5731,28 @@ nsDocument::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
   nsCOMPtr<nsPIDOMWindowInner> window =
     do_QueryInterface(nsJSUtils::GetStaticScriptGlobal(global));
 
-  if (window) {
+  return IsWebComponentsEnabled(window);
+}
+
+bool
+nsDocument::IsWebComponentsEnabled(dom::NodeInfo* aNodeInfo)
+{
+  if (Preferences::GetBool("dom.webcomponents.enabled")) {
+    return true;
+  }
+
+  nsIDocument* doc = aNodeInfo->GetDocument();
+  // Use GetScopeObject() here so that data documents work the same way as the
+  // main document they're associated with.
+  nsCOMPtr<nsPIDOMWindowInner> window =
+    do_QueryInterface(doc->GetScopeObject());
+  return IsWebComponentsEnabled(window);
+}
+
+bool
+nsDocument::IsWebComponentsEnabled(nsPIDOMWindowInner* aWindow)
+{
+  if (aWindow) {
     nsresult rv;
     nsCOMPtr<nsIPermissionManager> permMgr =
       do_GetService(NS_PERMISSIONMANAGER_CONTRACTID, &rv);
@@ -5739,7 +5760,7 @@ nsDocument::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
 
     uint32_t perm;
     rv = permMgr->TestPermissionFromWindow(
-      window, "moz-extremely-unstable-and-will-change-webcomponents", &perm);
+      aWindow, "moz-extremely-unstable-and-will-change-webcomponents", &perm);
     NS_ENSURE_SUCCESS(rv, false);
 
     return perm == nsIPermissionManager::ALLOW_ACTION;
diff --git a/dom/base/nsDocument.h b/dom/base/nsDocument.h
index adab0027edbb..a6eb8647d0e6 100644
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -1382,7 +1382,13 @@ public:
   virtual already_AddRefed<mozilla::dom::CustomElementRegistry>
     GetCustomElementRegistry() override;
 
+  // Check whether web components are enabled for the global of aObject.
   static bool IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject);
+  // Check whether web components are enabled for the global of the document
+  // this nodeinfo comes from.
+  static bool IsWebComponentsEnabled(mozilla::dom::NodeInfo* aNodeInfo);
+  // Check whether web components are enabled for the given window.
+  static bool IsWebComponentsEnabled(nsPIDOMWindowInner* aWindow);
 
   RefPtr<mozilla::EventListenerManager> mListenerManager;
   RefPtr<mozilla::dom::StyleSheetList> mDOMStyleSheets;
diff --git a/dom/html/HTMLContentElement.cpp b/dom/html/HTMLContentElement.cpp
index bbc780845713..01c0158a0387 100644
--- a/dom/html/HTMLContentElement.cpp
+++ b/dom/html/HTMLContentElement.cpp
@@ -6,6 +6,7 @@
 
 #include "mozilla/dom/HTMLContentElement.h"
 #include "mozilla/dom/HTMLContentElementBinding.h"
+#include "mozilla/dom/HTMLUnknownElement.h"
 #include "mozilla/dom/NodeListBinding.h"
 #include "mozilla/dom/ShadowRoot.h"
 #include "mozilla/css/StyleRule.h"
@@ -17,8 +18,28 @@
 #include "nsRuleProcessorData.h"
 #include "nsRuleWalker.h"
 #include "nsCSSParser.h"
+#include "nsDocument.h"
 
-NS_IMPL_NS_NEW_HTML_ELEMENT(Content)
+// Expand NS_IMPL_NS_NEW_HTML_ELEMENT(Content) to add check for web components
+// being enabled.
+nsGenericHTMLElement*
+NS_NewHTMLContentElement(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
+                         mozilla::dom::FromParser aFromParser)
+{
+  // When this check is removed, remove the nsDocument.h and
+  // HTMLUnknownElement.h includes.  Also remove nsINode::IsHTMLContentElement.
+  //
+  // We have to jump through some hoops to be able to produce both NodeInfo* and
+  // already_AddRefed<NodeInfo>& for our callees.
+  RefPtr<mozilla::dom::NodeInfo> nodeInfo(aNodeInfo);
+  if (!nsDocument::IsWebComponentsEnabled(nodeInfo)) {
+    already_AddRefed<mozilla::dom::NodeInfo> nodeInfoArg(nodeInfo.forget());
+    return new mozilla::dom::HTMLUnknownElement(nodeInfoArg);
+  }
+
+  already_AddRefed<mozilla::dom::NodeInfo> nodeInfoArg(nodeInfo.forget());
+  return new mozilla::dom::HTMLContentElement(nodeInfoArg);
+}
 
 using namespace mozilla::dom;
 
diff --git a/dom/html/HTMLShadowElement.cpp b/dom/html/HTMLShadowElement.cpp
index 3d4c6ab723e0..8824c2875f7f 100644
--- a/dom/html/HTMLShadowElement.cpp
+++ b/dom/html/HTMLShadowElement.cpp
@@ -8,10 +8,31 @@
 
 #include "ChildIterator.h"
 #include "nsContentUtils.h"
+#include "nsDocument.h"
 #include "mozilla/dom/HTMLShadowElement.h"
+#include "mozilla/dom/HTMLUnknownElement.h"
 #include "mozilla/dom/HTMLShadowElementBinding.h"
 
-NS_IMPL_NS_NEW_HTML_ELEMENT(Shadow)
+// Expand NS_IMPL_NS_NEW_HTML_ELEMENT(Shadow) to add check for web components
+// being enabled.
+nsGenericHTMLElement*
+NS_NewHTMLShadowElement(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
+                        mozilla::dom::FromParser aFromParser)
+{
+  // When this check is removed, remove the nsDocument.h and
+  // HTMLUnknownElement.h includes.  Also remove nsINode::IsHTMLShadowElement.
+  //
+  // We have to jump through some hoops to be able to produce both NodeInfo* and
+  // already_AddRefed<NodeInfo>& for our callees.
+  RefPtr<mozilla::dom::NodeInfo> nodeInfo(aNodeInfo);
+  if (!nsDocument::IsWebComponentsEnabled(nodeInfo)) {
+    already_AddRefed<mozilla::dom::NodeInfo> nodeInfoArg(nodeInfo.forget());
+    return new mozilla::dom::HTMLUnknownElement(nodeInfoArg);
+  }
+
+  already_AddRefed<mozilla::dom::NodeInfo> nodeInfoArg(nodeInfo.forget());
+  return new mozilla::dom::HTMLShadowElement(nodeInfoArg);
+}
 
 using namespace mozilla::dom;