Allow assertions to be enabled in Blink Release builds.

Source/wtf/text/ASCIIFastPath.h

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 101 matching lines @@
     for (;i < length && !isAlignedTo<memoryAccessMask>(&source[i]); ++i) {
         ASSERT(!(source[i] & 0xff00));
         destination[i] = static_cast<LChar>(source[i]);
     }
 
     const uintptr_t sourceLoadSize = 32; // Process 32 bytes (16 UChars) each iteration
     const size_t ucharsPerLoop = sourceLoadSize / sizeof(UChar);
     if (length > ucharsPerLoop) {
         const size_t endLength = length - ucharsPerLoop + 1;
         for (; i < endLength; i += ucharsPerLoop) {
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
             for (unsigned checkIndex = 0; checkIndex < ucharsPerLoop; ++checkIndex)
                 ASSERT(!(source[i+checkIndex] & 0xff00));
 #endif
             __m128i first8UChars = _mm_load_si128(reinterpret_cast<const __m128i*>(&source[i]));
             __m128i second8UChars = _mm_load_si128(reinterpret_cast<const __m128i*>(&source[i+8]));
             __m128i packedChars = _mm_packus_epi16(first8UChars, second8UChars);
             _mm_storeu_si128(reinterpret_cast<__m128i*>(&destination[i]), packedChars);
         }
     }
 
@@ skipping 29 matching lines @@
     for (size_t i = 0; i < length; ++i) {
         ASSERT(!(source[i] & 0xff00));
         destination[i] = static_cast<LChar>(source[i]);
     }
 #endif
 }
 
 } // namespace WTF
 
 #endif // ASCIIFastPath_h