feature: add native context types

src/Context.ts

@@ -86,7 +86,7 @@ var CONTEXT_PROPERTIES = [
   'globalAlpha',
   'globalCompositeOperation',
   'imageSmoothingEnabled',
-];
+] as const;
 
 const traceArrMax = 100;
 /**
@@ -701,6 +701,11 @@ export class Context {
   }
 }
 
+// supported context properties
+type CanvasContextProps = Pick<CanvasRenderingContext2D, typeof CONTEXT_PROPERTIES[number]>;
+
+export interface Context extends CanvasContextProps {};
+
 CONTEXT_PROPERTIES.forEach(function (prop) {
   Object.defineProperty(Context.prototype, prop, {
     get() {