Bug 1478823: Add a chrome DOM event signalling that the head element's children have been parsed. r=bzbarsky

Differential Revision: https://phabricator.services.mozilla.com/D2612

--HG--
extra : moz-landing-system : lando

dom/html/HTMLSharedElement.cpp

@@ -12,6 +12,7 @@
 #include "mozilla/dom/HTMLParamElementBinding.h"
 #include "mozilla/dom/HTMLQuoteElementBinding.h"
 
+#include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/MappedDeclarations.h"
 #include "nsAttrValueInlines.h"
 #include "nsStyleConsts.h"
@@ -56,6 +57,21 @@ HTMLSharedElement::GetHref(nsAString& aValue)
   CopyUTF8toUTF16(spec, aValue);
 }
 
+void
+HTMLSharedElement::DoneAddingChildren(bool aHaveNotified)
+{
+  if (mNodeInfo->Equals(nsGkAtoms::head)) {
+    RefPtr<AsyncEventDispatcher> asyncDispatcher =
+      new AsyncEventDispatcher(this,
+                              NS_LITERAL_STRING("DOMHeadElementParsed"),
+                              CanBubble::eYes,
+                              ChromeOnlyDispatch::eYes);
+    // Always run async in order to avoid running script when the content
+    // sink isn't expecting it.
+    asyncDispatcher->PostDOMEvent();
+  }
+}
+
 bool
 HTMLSharedElement::ParseAttribute(int32_t aNamespaceID,
                                   nsAtom* aAttribute,

dom/html/HTMLSharedElement.h

@@ -30,6 +30,8 @@ public:
   }
 
   // nsIContent
+  virtual void DoneAddingChildren(bool aHaveNotified) override;
+
   virtual bool ParseAttribute(int32_t aNamespaceID,
                                 nsAtom* aAttribute,
                                 const nsAString& aValue,

parser/html/nsHtml5TreeBuilderCppSupplement.h

@@ -1109,7 +1109,8 @@ nsHtml5TreeBuilder::elementPopped(int32_t aNamespace,
   // properly (e.g. form state restoration).
   // XXX expose ElementName group here and do switch
   if (aName == nsGkAtoms::object || aName == nsGkAtoms::select ||
-      aName == nsGkAtoms::textarea || aName == nsGkAtoms::output) {
+      aName == nsGkAtoms::textarea || aName == nsGkAtoms::output ||
+      aName == nsGkAtoms::head) {
     if (mBuilder) {
       nsHtml5TreeOperation::DoneAddingChildren(
         static_cast<nsIContent*>(aElement));