Only populate line number in case parsing synchronously.

Source/core/html/parser/HTMLDocumentParser.h

Index: Source/core/html/parser/HTMLDocumentParser.h
diff --git a/Source/core/html/parser/HTMLDocumentParser.h b/Source/core/html/parser/HTMLDocumentParser.h
index bf19e2bbe26a427443d5e0de0991564c374cdc2b..73688c6c6157ae7c9137d4b3eff89f51f7d97865 100644
--- a/Source/core/html/parser/HTMLDocumentParser.h
+++ b/Source/core/html/parser/HTMLDocumentParser.h
@@ -83,6 +83,7 @@ public:
     HTMLTokenizer* tokenizer() const { return m_tokenizer.get(); }
 
     virtual TextPosition textPosition() const override final;
+    virtual bool hasLineNumber() const override final;
     virtual OrdinalNumber lineNumber() const override final;
 
     virtual void suspendScheduledTasks() override final;
@@ -203,6 +204,7 @@ private:
     bool m_tasksWereSuspended;
     unsigned m_pumpSessionNestingLevel;
     unsigned m_pumpSpeculationsSessionNestingLevel;
+    bool m_hasLineNumber;
 };
 
 }