Merge 159848 "Process decoded bytes when in stopped (but not det..."

Source/core/xml/parser/XMLDocumentParser.cpp

Index: Source/core/xml/parser/XMLDocumentParser.cpp
===================================================================
--- Source/core/xml/parser/XMLDocumentParser.cpp	(revision 160097)
+++ Source/core/xml/parser/XMLDocumentParser.cpp	(working copy)
@@ -1156,8 +1156,14 @@
     if (pi->isCSS())
         m_sawCSS = true;
     m_sawXSLTransform = !m_sawFirstElement && pi->isXSL();
-    if (m_sawXSLTransform && !document()->transformSourceDocument())
+    if (m_sawXSLTransform && !document()->transformSourceDocument()) {
+        // 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 to
+        // accumulate in m_originalSourceForTransform. So, we call stopParsing() here and
+        // check isStopped() in element callbacks.
+        // FIXME: This contradicts the contract of DocumentParser.
         stopParsing();
+    }
 }
 
 void XMLDocumentParser::cdataBlock(const String& text)