document.open() should remove the initial about:blank-ness of the doc…

…ument

https://bugs.webkit.org/show_bug.cgi?id=245445

Reviewed by Darin Adler and Youenn Fablet.

document.open() should remove the initial about:blank-ness of the document.
This aligns our behavior with Firefox and Chrome.

* LayoutTests/imported/w3c/web-platform-tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/remove-initial-about-blankness.window-expected.txt:
* Source/WebCore/dom/Document.cpp:
(WebCore::Document::open):

Canonical link: https://commits.webkit.org/254747@main

LayoutTests/imported/w3c/web-platform-tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/remove-initial-about-blankness.window-expected.txt

@@ -1,4 +1,4 @@
 
-FAIL document.open() removes the initial about:blank-ness of the document assert_equals: expected (undefined) undefined but got (string) "Hello world!"
+PASS document.open() removes the initial about:blank-ness of the document
 PASS Double-check: without document.open(), Window reuse indeed happens
 

Source/WebCore/dom/Document.cpp

@@ -3044,8 +3044,13 @@ ExceptionOr<void> Document::open(Document* entryDocument)
     if (ScriptableDocumentParser* parser = scriptableDocumentParser())
         parser->setWasCreatedByScript(true);
 
-    if (m_frame)
+    if (m_frame) {
+        // Set document's is initial about:blank to false.
+        // https://html.spec.whatwg.org/multipage/dynamic-markup-insertion.html#document-open-steps (step 13)
+        m_frame->loader().advanceStatePastInitialEmptyDocument();
+
         m_frame->loader().didExplicitOpen();
+    }
 
     return { };
 }

Source/WebCore/loader/FrameLoader.cpp

@@ -4333,6 +4333,14 @@ bool FrameLoader::shouldSuppressTextInputFromEditing() const
     return m_frame.settings().shouldSuppressTextInputFromEditingDuringProvisionalNavigation() && m_state == FrameState::Provisional;
 }
 
+void FrameLoader::advanceStatePastInitialEmptyDocument()
+{
+    if (stateMachine().committingFirstRealLoad())
+        stateMachine().advanceTo(FrameLoaderStateMachine::DisplayingInitialEmptyDocumentPostCommit);
+    if (stateMachine().isDisplayingInitialEmptyDocument() && stateMachine().committedFirstRealDocumentLoad())
+        stateMachine().advanceTo(FrameLoaderStateMachine::CommittedFirstRealLoad);
+}
+
 } // namespace WebCore
 
 #undef PAGE_ID

Source/WebCore/loader/FrameLoader.h

@@ -271,6 +271,8 @@ class FrameLoader final {
     FrameLoaderStateMachine& stateMachine() { return m_stateMachine; }
     const FrameLoaderStateMachine& stateMachine() const { return m_stateMachine; }
 
+    void advanceStatePastInitialEmptyDocument();
+
     // FIXME: should return RefPtr.
     WEBCORE_EXPORT Frame* findFrameForNavigation(const AtomString& name, Document* activeDocument = nullptr);