Revert of Moved text decoding to the parser thread

Source/core/html/parser/HTMLTokenizer.h

Index: Source/core/html/parser/HTMLTokenizer.h
diff --git a/Source/core/html/parser/HTMLTokenizer.h b/Source/core/html/parser/HTMLTokenizer.h
index 3a4ca7f96a142ceacdf5d9faf0d390949ade7a0a..e1ea8ae28d9eb5a2c09ee2ef6a8292a03e300898 100644
--- a/Source/core/html/parser/HTMLTokenizer.h
+++ b/Source/core/html/parser/HTMLTokenizer.h
@@ -174,7 +174,7 @@ public:
     //  * CDATA sections in foreign content will be tokenized as bogus comments
     //    instead of as character tokens.
     //
-    void updateStateFor(const String& tagName);
+    void updateStateFor(const AtomicString& tagName);
 
     bool forceNullCharacterReplacement() const { return m_forceNullCharacterReplacement; }
     void setForceNullCharacterReplacement(bool value) { m_forceNullCharacterReplacement = value; }