Compiler doesn't validate usage of decorators on class fields

[pmdartus]

Description

Today the babel-plugin-transform-lwc-class throws when applying a decorator that is not imported to a class method.

export default class Test {
    @api
 // ^ Supported decorators (api, wire, track) should be imported from "engine"
    test() {}
}

But the same restriction doesn't get applied to properties. The following code passes compilation but doesn't work as expected at runtime.

export default class Test {
    @api test = false;
}