Bug 1444491 - Check the number of script blocking style sheets in autofocus algorithm r=hsivonen

Differential Revision: https://phabricator.services.mozilla.com/D165224

dom/base/Document.cpp

@@ -381,6 +381,7 @@
 #include "nsIX509Cert.h"
 #include "nsIX509CertValidity.h"
 #include "nsIXMLContentSink.h"
+#include "nsIHTMLContentSink.h"
 #include "nsIXULRuntime.h"
 #include "nsImageLoadingContent.h"
 #include "nsImportModule.h"
@@ -12790,6 +12791,27 @@ void Document::FlushAutoFocusCandidates() {
       iter.Remove();
       continue;
     }
+
+    nsCOMPtr<nsIContentSink> sink =
+        do_QueryInterface(autoFocusElementDoc->GetCurrentContentSink());
+    if (sink) {
+      nsHtml5TreeOpExecutor* executor =
+          static_cast<nsHtml5TreeOpExecutor*>(sink->AsExecutor());
+      if (executor) {
+        // This is a HTML5 document
+        MOZ_ASSERT(autoFocusElementDoc->IsHTMLDocument());
+        // If doc's script-blocking style sheet counter is greater than 0, th
+        // return.
+        if (executor->WaitForPendingSheets()) {
+          // In this case, element is the currently-best candidate, but doc is
+          // not ready for autofocusing. We'll try again next time flush
+          // autofocus candidates is called.
+          ScheduleFlushAutoFocusCandidates();
+          return;
+        }
+      }
+    }
+
     // The autofocus element could be moved to a different
     // top level BC.
     if (bc->Top()->GetDocument() != this) {

dom/base/nsContentSink.h

@@ -169,6 +169,10 @@ class nsContentSink : public nsICSSLoaderObserver,
 
   Document* GetDocument() { return mDocument; }
 
+  // Later on we might want to make this more involved somehow
+  // (e.g. stop waiting after some timeout or whatnot).
+  bool WaitForPendingSheets() { return mPendingSheetCount > 0; }
+
  protected:
   inline int32_t GetNotificationInterval() {
     if (mDynamicLowerValue) {
@@ -180,10 +184,6 @@ class nsContentSink : public nsICSSLoaderObserver,
 
   virtual nsresult FlushTags() = 0;
 
-  // Later on we might want to make this more involved somehow
-  // (e.g. stop waiting after some timeout or whatnot).
-  bool WaitForPendingSheets() { return mPendingSheetCount > 0; }
-
   void DoProcessLinkHeader();
 
   void StopDeflecting() {

dom/html/nsHTMLContentSink.cpp

@@ -114,6 +114,7 @@ class HTMLContentSink : public nsContentSink, public nsIHTMLContentSink {
   virtual void SetDocumentCharset(NotNull<const Encoding*> aEncoding) override;
   virtual nsISupports* GetTarget() override;
   virtual bool IsScriptExecuting() override;
+  virtual bool WaitForPendingSheets() override;
   virtual void ContinueInterruptedParsingAsync() override;
 
   // nsIHTMLContentSink
@@ -924,6 +925,10 @@ void HTMLContentSink::ContinueInterruptedParsingIfEnabled() {
   }
 }
 
+bool HTMLContentSink::WaitForPendingSheets() {
+  return nsContentSink::WaitForPendingSheets();
+}
+
 void HTMLContentSink::ContinueInterruptedParsingAsync() {
   nsCOMPtr<nsIRunnable> ev = NewRunnableMethod(
       "HTMLContentSink::ContinueInterruptedParsingIfEnabled", this,

parser/html/nsHtml5TreeOpExecutor.h

@@ -131,6 +131,8 @@ class nsHtml5TreeOpExecutor final
    */
   void WillResume() override;
 
+  virtual nsIContentSink* AsExecutor() override { return this; }
+
   virtual void InitialTranslationCompleted() override;
 
   /**

parser/htmlparser/nsIContentSink.h

@@ -89,6 +89,12 @@ class nsIContentSink : public nsISupports {
    */
   virtual void WillResume() = 0;
 
+  /**
+   * This method returns nullptr unless `this` can
+   * be cast as nsHtml5TreeOpExecutor.
+   */
+  virtual nsIContentSink* AsExecutor() { return nullptr; }
+
   /**
    * This method gets called by the parser so that the content
    * sink can retain a reference to the parser. The expectation

parser/htmlparser/nsIHTMLContentSink.h

@@ -83,6 +83,12 @@ class nsIHTMLContentSink : public nsIContentSink {
    * @param  aTag - The tag to be closed.
    */
   NS_IMETHOD CloseContainer(ElementType aTag) = 0;
+
+  /**
+   *  This method returns true if there are more than one
+   *  pending style sheets, false otherwise.
+   */
+  virtual bool WaitForPendingSheets() = 0;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIHTMLContentSink, NS_IHTML_CONTENT_SINK_IID)

testing/web-platform/tests/html/interaction/focus/the-autofocus-attribute/spin-by-blocking-style-sheet.html

@@ -2,11 +2,12 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="resources/utils.js"></script>
-<link rel="stylesheet" href="resources/erase-first.css?pipe=trickle(d1)">
 
 <input id="first" autofocus>
 <input id="second" autofocus>
 
+<link rel="stylesheet" href="resources/erase-first.css?pipe=trickle(d1)">
+
 <script>
 'use strict';