Make image decoders faster by refactoring hot loops that fills the lines of ImageFrame.

Source/core/platform/image-decoders/png/PNGImageDecoder.cpp

Index: Source/core/platform/image-decoders/png/PNGImageDecoder.cpp
diff --git a/Source/core/platform/image-decoders/png/PNGImageDecoder.cpp b/Source/core/platform/image-decoders/png/PNGImageDecoder.cpp
index beb9a1dc8e6ee7c9e0cb688b7b18ca3e0da0c093..ae1735aceab7978f6f66747d2f0cb596b641f7b4 100644
--- a/Source/core/platform/image-decoders/png/PNGImageDecoder.cpp
+++ b/Source/core/platform/image-decoders/png/PNGImageDecoder.cpp
@@ -488,16 +488,11 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer, unsigned rowIndex,
 #endif
 
     // Write the decoded row pixels to the frame buffer.
-    ImageFrame::PixelData* address = buffer.getAddr(0, y);
     bool nonTrivialAlpha = false;
-    int width = size().width();
-
-    png_bytep pixel = row;
-    for (int x = 0; x < width; ++x, pixel += colorChannels) {
-        unsigned alpha = hasAlpha ? pixel[3] : 255;
-        buffer.setRGBA(address++, pixel[0], pixel[1], pixel[2], alpha);
-        nonTrivialAlpha |= alpha < 255;
-    }
+    if (hasAlpha)
+        buffer.fillRowFromRGBASourceWithNonTrivialAlphaDetection(y, row, nonTrivialAlpha);
+    else
+        buffer.fillRowFromRGBSource(y, row);
 
     if (nonTrivialAlpha && !buffer.hasAlpha())
         buffer.setHasAlpha(nonTrivialAlpha);