feat(types): mixins/extends support in TypeScript (#626)

packages/reactivity/__tests__/collections/Set.spec.ts

@@ -412,13 +412,13 @@ describe('reactivity/collections', () => {
         `Reactive Set contains both the raw and reactive`
       ).toHaveBeenWarned()
     })
-    
+
     it('thisArg', () => {
-      const raw = new Set([ 'value' ])
+      const raw = new Set(['value'])
       const proxy = reactive(raw)
       const thisArg = {}
       let count = 0
-      proxy.forEach(function (this :{}, value, _, set) {
+      proxy.forEach(function(this: {}, value, _, set) {
         ++count
         expect(this).toBe(thisArg)
         expect(value).toBe('value')

packages/reactivity/src/baseHandlers.ts

@@ -49,7 +49,7 @@ function createGetter(isReadonly = false, shallow = false) {
     }
     const res = Reflect.get(target, key, receiver)
 
-    if (isSymbol(key) && builtInSymbols.has(key) || key === '__proto__') {
+    if ((isSymbol(key) && builtInSymbols.has(key)) || key === '__proto__') {
       return res
     }