LibWeb: Simplify generation of perspective() matrix transform

A value of `perspective(none)` should result in the identity matrix. But
instead of creating that identity matrix explicitly, just break and
default to the identity matrix at the bottom of this method.

Author: gmta

Libraries/LibWeb/CSS/Transformation.cpp

@@ -90,10 +90,7 @@ ErrorOr<Gfx::FloatMatrix4x4> Transformation::to_matrix(Optional<Painting::Painta
                 0, 0, 1, 0,
                 0, 0, -1 / distance, 1);
         }
-        return Gfx::FloatMatrix4x4(1, 0, 0, 0,
-            0, 1, 0, 0,
-            0, 0, 1, 0,
-            0, 0, 0, 1);
+        break;
     case CSS::TransformFunction::Matrix:
         if (count == 6)
             return Gfx::FloatMatrix4x4(TRY(value(0)), TRY(value(2)), 0, TRY(value(4)),