gdiplus: Fix a possible floating point exception in path gradients.

dlls/gdiplus/graphics.c

@@ -1493,9 +1493,18 @@ static GpStatus brush_fill_pixels(GpGraphics *graphics, GpBrush *brush,
                         REAL blend_amount, pdy, pdx;
                         pdy = yf - center_point.Y;
                         pdx = xf - center_point.X;
+
+                        if (fabs(pdx) <= 0.001 && fabs(pdy) <= 0.001)
+                        {
+                            /* Too close to center point, don't try to calculate outer color */
+                            outer_color = start_color;
+                        }
+                        else
+                        {
                             blend_amount = ( (center_point.Y - start_point.Y) * pdx + (start_point.X - center_point.X) * pdy ) / ( dy * pdx - dx * pdy );
                             outer_color = blend_colors(start_color, end_color, blend_amount);
                         }
+                    }
 
                     distance = (end_point.Y - start_point.Y) * (start_point.X - xf) +
                         (end_point.X - start_point.X) * (yf - start_point.Y);