[css-paint-api] Use of "the" to refer to PaintWorkletGlobalScope is misleading

[bzbarsky]

In https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet there are normative sentences like:

The PaintWorkletGlobalScope is the global execution context of the paintWorklet.

and

The PaintWorkletGlobalScope has a devicePixelRatio property which is identical to the Window.devicePixelRatio property.

In https://drafts.css-houdini.org/css-paint-api-1/#concepts there is a sentence like this:

A paint definition is a struct which describes the information needed by the PaintWorkletGlobalScope [...]

and in https://drafts.css-houdini.org/css-paint-api-1/#registering-custom-paint a sentence like this:

The PaintWorkletGlobalScope has a map of paint class instances.

All of these make it sound like there is only one PaintWorkletGlobalScope. This is later contradicted by normative requirements in https://drafts.css-houdini.org/css-paint-api-1/#drawing-an-image step 12.

I believe all of those should be using "a", not "the". Furthermore, "the global execution context" should probably be "a global execution context" or something...