Use same parameters for jpeg decoding quality on all platforms.

Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * Portions are Copyright (C) 2001-6 mozilla.org
  *
  * Other contributors:
  *   Stuart Parmenter <stuart@mozilla.com>
  *
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  *
@@ skipping 56 matching lines @@
 #else // Output little-endian BGRA pixels.
 inline J_COLOR_SPACE rgbOutputColorSpace() { return JCS_EXT_BGRA; }
 #endif
 inline bool turboSwizzled(J_COLOR_SPACE colorSpace) { return colorSpace == JCS_EXT_RGBA || colorSpace == JCS_EXT_BGRA; }
 inline bool colorSpaceHasAlpha(J_COLOR_SPACE colorSpace) { return turboSwizzled(colorSpace); }
 #else
 inline J_COLOR_SPACE rgbOutputColorSpace() { return JCS_RGB; }
 inline bool colorSpaceHasAlpha(J_COLOR_SPACE) { return false; }
 #endif
 
-#if USE(LOW_QUALITY_IMAGE_NO_JPEG_DITHERING)
-inline J_DCT_METHOD dctMethod() { return JDCT_IFAST; }
-inline J_DITHER_MODE ditherMode() { return JDITHER_NONE; }
-#else
 inline J_DCT_METHOD dctMethod() { return JDCT_ISLOW; }
 inline J_DITHER_MODE ditherMode() { return JDITHER_FS; }
-#endif
-
-#if USE(LOW_QUALITY_IMAGE_NO_JPEG_FANCY_UPSAMPLING)
-inline bool doFancyUpsampling() { return false; }
-#else
 inline bool doFancyUpsampling() { return true; }
-#endif
 
 namespace {
 
 const int exifMarker = JPEG_APP0 + 1;
 
 // JPEG only supports a denominator of 8.
 const unsigned scaleDenominator = 8;
 
 } // namespace
 
@@ skipping 912 matching lines @@
     // has failed.
     if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
         setFailed();
     // If we're done decoding the image, we don't need the JPEGImageReader
     // anymore.  (If we failed, |m_reader| has already been cleared.)
     else if ((!m_frameBufferCache.isEmpty() && (m_frameBufferCache[0].status() == ImageFrame::FrameComplete)) || (hasImagePlanes() && !onlySize))
         m_reader.clear();
 }
 
 }