Support "await a stable state" and "provide a stable state"

Source/core/html/parser/HTMLScriptRunner.cpp

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/html/parser/HTMLScriptRunner.h"
 
 #include "bindings/v8/ScriptSourceCode.h"
 #include "core/dom/Element.h"
-#include "core/events/Event.h"
 #include "core/dom/IgnoreDestructiveWriteCountIncrementer.h"
 #include "core/dom/Microtask.h"
 #include "core/dom/ScriptLoader.h"
+#include "core/events/Event.h"
 #include "core/fetch/ScriptResource.h"
+#include "core/frame/Frame.h"
+#include "core/html/StableState.h"
 #include "core/html/parser/HTMLInputStream.h"
 #include "core/html/parser/HTMLScriptRunnerHost.h"
 #include "core/html/parser/NestingLevelIncrementer.h"
-#include "core/frame/Frame.h"
 #include "platform/NotImplemented.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 HTMLScriptRunner::HTMLScriptRunner(Document* document, HTMLScriptRunnerHost* host)
     : m_document(document)
     , m_host(host)
     , m_scriptNestingLevel(0)
@@ skipping 231 matching lines @@
         // This contains both and ASSERTION and a null check since we should not
         // be getting into the case of a null script element, but seem to be from
         // time to time. The assertion is left in to help find those cases and
         // is being tracked by <https://bugs.webkit.org/show_bug.cgi?id=60559>.
         ASSERT(scriptLoader);
         if (!scriptLoader)
             return;
 
         ASSERT(scriptLoader->isParserInserted());
 
-        if (!isExecutingScript())
+        if (!isExecutingScript()) {
             Microtask::performCheckpoint();
+            StableState::provide();
+        }
 
         InsertionPointRecord insertionPointRecord(m_host->inputStream());
         NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel);
 
         scriptLoader->prepareScript(scriptStartPosition);
 
         if (!scriptLoader->willBeParserExecuted())
             return;
 
         if (scriptLoader->willExecuteWhenDocumentFinishedParsing()) {
             requestDeferredScript(script);
         } else if (scriptLoader->readyToBeParserExecuted()) {
             if (m_scriptNestingLevel == 1) {
                 m_parserBlockingScript.setElement(script);
                 m_parserBlockingScript.setStartingPosition(scriptStartPosition);
             } else {
                 ScriptSourceCode sourceCode(script->textContent(), documentURLForScriptExecution(m_document), scriptStartPosition);
                 scriptLoader->executeScript(sourceCode);
             }
         } else {
             requestParsingBlockingScript(script);
         }
     }
 }
 
 }