LibGfx+LibMedia+LibWeb: Use new Matrix subscript operator

Author: https://github.com/ion232
Commit: 9a8599f265
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5613
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/Painting/StackingContext.cpp

@@ -293,10 +293,9 @@ Gfx::AffineTransform StackingContext::affine_transform_matrix() const
 
 static Gfx::FloatMatrix4x4 matrix_with_scaled_translation(Gfx::FloatMatrix4x4 matrix, float scale)
 {
-    auto* m = matrix.elements();
-    m[0][3] *= scale;
-    m[1][3] *= scale;
-    m[2][3] *= scale;
+    matrix[0, 3] *= scale;
+    matrix[1, 3] *= scale;
+    matrix[2, 3] *= scale;
     return matrix;
 }