Rather than specifying a cx for every single CSS property from Stylo, we
instead make it implicit. This allows us to remove the `CanGc::note()`
from the macro and pass in the `cx` as normal.
We can use a similar approach for setters in other elements where we use
the setter macros.
Part of #42812
Testing: It compiles
Signed-off-by: Tim van der Lippe <tvanderlippe@gmail.com>