fix(core): add warn for missing static flag for @ViewChild (#1673)
fix(core): add warn for missing static flag for @ViewChild (#1673)

fix #1633
formly-js/ng2-formly,formly-js/ng2-formly,ngx-formly/ngx-formly,formly-js/ng-formly,ngx-formly/ngx-formly,formly-js/ng2-formly,formly-js/ng-formly,ngx-formly/ngx-formly,ngx-formly/ngx-formly