Clarify supported context formats definition

[beaufortfrancois]

The following definition of supported context formats is slightly confusing because of the word "initially". It reads as if this could evolve during the life of the app.

The supported context formats are a set of GPUTextureFormats that must be supported when specified as a GPUCanvasConfiguration.format regardless of the given GPUCanvasConfiguration.device, initially set to: «"bgra8unorm", "rgba8unorm", "rgba16float"».

May I suggest we remove the word "initially" to avoid confusion?

[toji]

"initially set to" is just how most W3C specs initialize values in the spec, but I agree that removing "initially" here helps with spec comprehension without being ambiguous.