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

Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp

Index: Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp
diff --git a/Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp b/Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp
index 26171f55dae281d37ebcb21ce8f08c8b957750ed..744e17d9e0d518f4ecfb87f5406dc1df85620b8a 100644
--- a/Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp
+++ b/Source/core/platform/image-decoders/webp/WEBPImageDecoder.cpp
@@ -194,8 +194,16 @@ void WEBPImageDecoder::applyColorProfile(const uint8_t* data, size_t dataSize, I
         if (qcms_transform* transform = colorTransform())
             qcms_transform_data_type(transform, row, row, width, QCMS_OUTPUT_RGBX);
         uint8_t* pixel = row;
-        for (int x = 0; x < width; ++x, pixel += 4)
-            buffer.setRGBA(x, y, pixel[0], pixel[1], pixel[2], pixel[3]);
+
+        // Do not merge the loops below. They are hand rolled for each case for maximal peformace.
+        ImageFrame::PixelData* dst = buffer.getAddr(0, y);
+        if (buffer.premultiplyAlpha()) {
+            for (int x = 0; x < width; ++x, pixel += 4)
+                buffer.setRGBAPremultiply(dst + x, pixel[0], pixel[1], pixel[2], pixel[3]);
+        } else {
+            for (int x = 0; x < width; ++x, pixel += 4)
+                buffer.setRGBANoPremultiply(dst + x, pixel[0], pixel[1], pixel[2], pixel[3]);
+        }
     }
 
     m_decodedHeight = decodedHeight;