Only populate line number in case parsing synchronously.

Source/core/html/parser/HTMLDocumentParser.cpp

Index: Source/core/html/parser/HTMLDocumentParser.cpp
diff --git a/Source/core/html/parser/HTMLDocumentParser.cpp b/Source/core/html/parser/HTMLDocumentParser.cpp
index c7fc2c6758a7e9a5a4ab7963765ce371c79d535c..8a8e9b4a344311537b2dc6704806fcde8d518c8e 100644
--- a/Source/core/html/parser/HTMLDocumentParser.cpp
+++ b/Source/core/html/parser/HTMLDocumentParser.cpp
@@ -45,6 +45,7 @@
 #include "platform/TraceEvent.h"
 #include "public/platform/WebThreadedDataReceiver.h"
 #include "wtf/Functional.h"
+#include "wtf/TemporaryChange.h"
 
 namespace blink {
 
@@ -119,6 +120,7 @@ HTMLDocumentParser::HTMLDocumentParser(HTMLDocument& document, bool reportErrors
     , m_tasksWereSuspended(false)
     , m_pumpSessionNestingLevel(0)
     , m_pumpSpeculationsSessionNestingLevel(0)
+    , m_hasLineNumber(false)
 {
     ASSERT(shouldUseThreading() || (m_token && m_tokenizer));
 }
@@ -415,6 +417,7 @@ void HTMLDocumentParser::discardSpeculationsAndResumeFrom(PassOwnPtr<ParsedChunk
 size_t HTMLDocumentParser::processParsedChunkFromBackgroundParser(PassOwnPtr<ParsedChunk> popChunk)
 {
     TRACE_EVENT0("blink", "HTMLDocumentParser::processParsedChunkFromBackgroundParser");
+    TemporaryChange<bool> hasLineNumber(m_hasLineNumber, true);
 
     ASSERT_WITH_SECURITY_IMPLICATION(document()->activeParserCount() == 1);
     ASSERT(!isParsingFragment());
@@ -489,6 +492,8 @@ size_t HTMLDocumentParser::processParsedChunkFromBackgroundParser(PassOwnPtr<Par
     if (!isStopped())
         m_treeBuilder->flush(FlushIfAtTextLimit);
 
+    m_hasLineNumber = false;
+
     return elementTokenCount;
 }
 
@@ -907,6 +912,11 @@ bool HTMLDocumentParser::isExecutingScript() const
     return m_scriptRunner->isExecutingScript();
 }
 
+bool HTMLDocumentParser::isParsingAtLineNumber() const
+{
+    return m_hasLineNumber && ScriptableDocumentParser::isParsingAtLineNumber();
+}
+
 OrdinalNumber HTMLDocumentParser::lineNumber() const
 {
     if (m_haveBackgroundParser)