Bug 1282566 (Part 2) - Remove some unused fields from nsPNGDecoder. r=edwin

image/decoders/nsPNGDecoder.cpp

@@ -101,7 +101,6 @@ nsPNGDecoder::nsPNGDecoder(RasterImage* aImage)
  , mInProfile(nullptr)
  , mTransform(nullptr)
  , format(gfx::SurfaceFormat::UNKNOWN)
- , mHeaderBytesRead(0)
  , mCMSMode(0)
  , mChannels(0)
  , mPass(0)

image/decoders/nsPNGDecoder.h

@@ -95,10 +95,6 @@ public:
 
   gfx::SurfaceFormat format;
 
-  // For metadata decodes.
-  uint8_t mSizeBytes[8]; // Space for width and height, both 4 bytes
-  uint32_t mHeaderBytesRead;
-
   // whether CMS or premultiplied alpha are forced off
   uint32_t mCMSMode;