React.ComponentType<any> flagged as unused when used as a param type in a method.

```
function renderTab(Tab: React.ComponentType): null {
return null;
}

class Foo extends React.Component {
renderTab(Tab: React.ComponentType): null { // 'ComponentType' is not defined. eslint(no-undef)
return null;
}
}
```
`eslint` only complains about the use of `ComponentType` when used as a param type in a method, but functions are fine.

This is using 5.7.2 of eslint-plugin-flowtype.

Reproduce the report with the standalone function and class method snippets using eslint-plugin-flowtype 5.7.2, then trace the rule handling Flow parameter annotations in methods. Done means React.ComponentType is not falsely reported as undefined in the method case while the existing function behavior remains correct.

Written by the indexing model from the issue text.