Backout patch from bug 389366 because it does not have M9 approval.

content/canvas/src/nsCanvasRenderingContext2D.cpp

@@ -2465,13 +2465,6 @@ nsCanvasRenderingContext2D::GetImageData()
             PRUint8 g = *row++;
             PRUint8 b = *row++;
 #endif
-            // Convert to non-premultiplied color
-            if (a != 0) {
-                r = (r * 255) / a;
-                g = (g * 255) / a;
-                b = (b * 255) / a;
-            }
-
             *dest++ = INT_TO_JSVAL(r);
             *dest++ = INT_TO_JSVAL(g);
             *dest++ = INT_TO_JSVAL(b);
@@ -2595,11 +2588,6 @@ nsCanvasRenderingContext2D::PutImageData()
             else if (JSVAL_IS_DOUBLE(va)) ia = (PRUint8) (*JSVAL_TO_DOUBLE(va));
             else return NS_ERROR_DOM_SYNTAX_ERR;
 
-            // Convert to premultiplied color (losslessly if the input came from getImageData)
-            ir = (ir*ia + 254) / 255;
-            ig = (ig*ia + 254) / 255;
-            ib = (ib*ia + 254) / 255;
-
 #ifdef IS_LITTLE_ENDIAN
             *imgPtr++ = ib;
             *imgPtr++ = ig;