Consider whether to allow trailing commas #1243

A common usability enhancement in programming languages is to allow trailing commas when defining data structures. This doesn't work in WGSL and the code below is invalid.

var pos : array<vec2<f32>, 3> = array<vec2<f32>, 3>(
  vec2<f32>(-1.0, -1.0),
  vec2<f32>( 1.0, -1.0),
  vec2<f32>(-1.0,  1.0),
);

Could we consider allowing trailing commas so that copy pasting lines like this works as expected and matches other languages? Having the function-like constructors might make this awkward though.