Implement a part of ProcessingInstruction by using PrivateScript

Source/core/xml/parser/XMLDocumentParser.cpp

Index: Source/core/xml/parser/XMLDocumentParser.cpp
diff --git a/Source/core/xml/parser/XMLDocumentParser.cpp b/Source/core/xml/parser/XMLDocumentParser.cpp
index 37d889a20265aed4203f654473a0db8e86d5e82b..15bf8a73a65ee7656c244ab7787b78e77c0541c1 100644
--- a/Source/core/xml/parser/XMLDocumentParser.cpp
+++ b/Source/core/xml/parser/XMLDocumentParser.cpp
@@ -100,9 +100,20 @@ static inline AtomicString toAtomicString(const xmlChar* string)
     return AtomicString::fromUTF8(reinterpret_cast<const char*>(string));
 }
 
+static bool xsltTransformed(Document* document)
+{
+    if (!RuntimeEnabledFeatures::xsltInPrivateScriptEnabled())
+        return document->transformSourceDocument();
+
+    bool xsltTransformed;
+    if (!V8Document::PrivateScript::xsltTransformedMethod(document->frame(), document, &xsltTransformed))
+        return false;
+    return xsltTransformed;
+}
+
 static inline bool hasNoStyleInformation(Document* document)
 {
-    if (document->sawElementsInKnownNamespaces() || document->transformSourceDocument())
+    if (document->sawElementsInKnownNamespaces() || xsltTransformed(document))
         return false;
 
     if (!document->frame() || !document->frame()->page())
@@ -1156,7 +1167,7 @@ void XMLDocumentParser::processingInstruction(const String& target, const String
         return;
 
     m_sawXSLTransform = !m_sawFirstElement && pi->isXSL();
-    if (m_sawXSLTransform && !document()->transformSourceDocument()) {
+    if (m_sawXSLTransform && !xsltTransformed(document())) {
         // This behavior is very tricky. We call stopParsing() here because we
         // want to stop processing the document until we're ready to apply the
         // transform, but we actually still want to be fed decoded string pieces