Allow assertions to be enabled in Blink Release builds.

Source/core/html/parser/BackgroundHTMLParser.cpp

Index: Source/core/html/parser/BackgroundHTMLParser.cpp
diff --git a/Source/core/html/parser/BackgroundHTMLParser.cpp b/Source/core/html/parser/BackgroundHTMLParser.cpp
index 66a62b8d1e77979e627500f19eb0851da2e89e22..13d18ab2ddc8b9e7db4876e69decd911e56356e7 100644
--- a/Source/core/html/parser/BackgroundHTMLParser.cpp
+++ b/Source/core/html/parser/BackgroundHTMLParser.cpp
@@ -54,7 +54,7 @@ static const size_t pendingTokenLimit = 1000;
 
 using namespace HTMLNames;
 
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
 
 static void checkThatTokensAreSafeToSendToAnotherThread(const CompactHTMLTokenStream* tokens)
 {
@@ -239,7 +239,7 @@ void BackgroundHTMLParser::sendTokensToMainThread()
     if (m_pendingTokens->isEmpty())
         return;
 
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
     checkThatTokensAreSafeToSendToAnotherThread(m_pendingTokens.get());
     checkThatPreloadsAreSafeToSendToAnotherThread(m_pendingPreloads);
     checkThatXSSInfosAreSafeToSendToAnotherThread(m_pendingXSSInfos);