diff --git a/parser/htmlparser/nsExpatDriver.cpp b/parser/htmlparser/nsExpatDriver.cpp
index 2d18786f77b6..61fc02a817c1 100644
--- a/parser/htmlparser/nsExpatDriver.cpp
+++ b/parser/htmlparser/nsExpatDriver.cpp
@@ -1228,7 +1228,7 @@ void nsExpatDriver::ParseBuffer(const char16_t* aBuffer, uint32_t aLength,
 }
 
 NS_IMETHODIMP
-nsExpatDriver::ConsumeToken(nsScanner& aScanner, bool& aFlushTokens) {
+nsExpatDriver::ConsumeToken(nsScanner& aScanner) {
   // We keep the scanner pointing to the position where Expat will start
   // parsing.
   nsScannerIterator currentExpatPosition;
diff --git a/parser/htmlparser/nsHTMLTokenizer.cpp b/parser/htmlparser/nsHTMLTokenizer.cpp
index ca4a5c7f4ff2..ed65809a013b 100644
--- a/parser/htmlparser/nsHTMLTokenizer.cpp
+++ b/parser/htmlparser/nsHTMLTokenizer.cpp
@@ -46,7 +46,6 @@ nsresult nsHTMLTokenizer::WillTokenize(bool aIsFinalChunk) { return NS_OK; }
  *                      reach a <script>).
  * @return Success or error
  */
-nsresult nsHTMLTokenizer::ConsumeToken(nsScanner& aScanner,
-                                       bool& aFlushTokens) {
+nsresult nsHTMLTokenizer::ConsumeToken(nsScanner& aScanner) {
   return NS_ERROR_HTMLPARSER_EOF;
 }
diff --git a/parser/htmlparser/nsITokenizer.h b/parser/htmlparser/nsITokenizer.h
index b51f060f8b2f..1a69ba15c896 100644
--- a/parser/htmlparser/nsITokenizer.h
+++ b/parser/htmlparser/nsITokenizer.h
@@ -32,13 +32,13 @@ class nsITokenizer : public nsISupports {
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITOKENIZER_IID)
 
   NS_IMETHOD WillTokenize(bool aIsFinalChunk) = 0;
-  NS_IMETHOD ConsumeToken(nsScanner& aScanner, bool& aFlushTokens) = 0;
+  NS_IMETHOD ConsumeToken(nsScanner& aScanner) = 0;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsITokenizer, NS_ITOKENIZER_IID)
 
 #define NS_DECL_NSITOKENIZER                            \
   NS_IMETHOD WillTokenize(bool aIsFinalChunk) override; \
-  NS_IMETHOD ConsumeToken(nsScanner& aScanner, bool& aFlushTokens) override;
+  NS_IMETHOD ConsumeToken(nsScanner& aScanner) override;
 
 #endif
diff --git a/parser/htmlparser/nsParser.cpp b/parser/htmlparser/nsParser.cpp
index 0bac003c8263..205deefbedc9 100644
--- a/parser/htmlparser/nsParser.cpp
+++ b/parser/htmlparser/nsParser.cpp
@@ -37,10 +37,8 @@
 
 using namespace mozilla;
 
-#define NS_PARSER_FLAG_OBSERVERS_ENABLED 0x00000004
-#define NS_PARSER_FLAG_PENDING_CONTINUE_EVENT 0x00000008
-#define NS_PARSER_FLAG_FLUSH_TOKENS 0x00000020
-#define NS_PARSER_FLAG_CAN_TOKENIZE 0x00000040
+#define NS_PARSER_FLAG_PENDING_CONTINUE_EVENT 0x00000001
+#define NS_PARSER_FLAG_CAN_TOKENIZE 0x00000002
 
 //-------------- Begin ParseContinue Event Definition ------------------------
 /*
@@ -137,7 +135,7 @@ void nsParser::Initialize(bool aConstructor) {
   mStreamStatus = NS_OK;
   mCommand = eViewNormal;
   mBlocked = 0;
-  mFlags = NS_PARSER_FLAG_OBSERVERS_ENABLED | NS_PARSER_FLAG_CAN_TOKENIZE;
+  mFlags = NS_PARSER_FLAG_CAN_TOKENIZE;
 
   mProcessingNetworkData = false;
   mIsAboutBlank = false;
@@ -786,9 +784,6 @@ nsParser::ParseFragment(const nsAString& aSourceBuffer,
   uint32_t theCount = aTagStack.Length();
   uint32_t theIndex = 0;
 
-  // Disable observers for fragments
-  mFlags &= ~NS_PARSER_FLAG_OBSERVERS_ENABLED;
-
   for (theIndex = 0; theIndex < theCount; theIndex++) {
     theContext.Append('<');
     theContext.Append(aTagStack[theCount - theIndex - 1]);
@@ -805,7 +800,6 @@ nsParser::ParseFragment(const nsAString& aSourceBuffer,
   // pass false for the aLastCall parameter.
   result = Parse(theContext, (void*)&theContext, false);
   if (NS_FAILED(result)) {
-    mFlags |= NS_PARSER_FLAG_OBSERVERS_ENABLED;
     return result;
   }
 
@@ -855,8 +849,6 @@ nsParser::ParseFragment(const nsAString& aSourceBuffer,
     }
   }
 
-  mFlags |= NS_PARSER_FLAG_OBSERVERS_ENABLED;
-
   return result;
 }
 
@@ -1368,15 +1360,12 @@ nsresult nsParser::Tokenize(bool aIsFinalChunk) {
   }
 
   if (NS_SUCCEEDED(result)) {
-    bool flushTokens = false;
-
     bool killSink = false;
 
     WillTokenize(aIsFinalChunk);
     while (NS_SUCCEEDED(result)) {
       mParserContext->mScanner->Mark();
-      result =
-          theTokenizer->ConsumeToken(*mParserContext->mScanner, flushTokens);
+      result = theTokenizer->ConsumeToken(*mParserContext->mScanner);
       if (NS_FAILED(result)) {
         mParserContext->mScanner->RewindToMark();
         if (NS_ERROR_HTMLPARSER_EOF == result) {
@@ -1387,13 +1376,6 @@ nsresult nsParser::Tokenize(bool aIsFinalChunk) {
           result = Terminate();
           break;
         }
-      } else if (flushTokens && (mFlags & NS_PARSER_FLAG_OBSERVERS_ENABLED)) {
-        // I added the extra test of NS_PARSER_FLAG_OBSERVERS_ENABLED to fix
-        // Bug# 23931. Flush tokens on seeing </SCRIPT> -- Ref: Bug# 22485 --
-        // Also remember to update the marked position.
-        mFlags |= NS_PARSER_FLAG_FLUSH_TOKENS;
-        mParserContext->mScanner->Mark();
-        break;
       }
     }