Computed properties context broken if prop with type array exist [TypeScript]

[ondrej-janosik]

Version

2.5.16

Reproduction link

https://github.com/ondrej-janosik/vue-bug-props/blob/master/src/App.vue

Steps to reproduce

1. Create a new project with VUE CLI, just add typescript
   
2. Open is VS code
3. Create a property in data in App.vue
   
4. Access this property in a computed method - works
   
5. Add prop with type array
   
6. Computed property context is broken - not work
   
7. Change prop type to for example to object - works
   

What is expected?

A computed property should have the same context even if prop with type array is presented

What is actually happening?

Computed property context is missing

[haoqunjiang]

Duplicate of #8406 #6841
Please keep an eye on #6856 - we'll start merging pull requests soon.