This commit fixes a bug in View Engine whereby the compiler errorneously
thinks that a method of a component has decorator metadata when that
method is one of those in `Object.prototype`, for example `toString`.
This bug is discovered in v10.0.4 of `@angular/language-service` after
the default bundle format was switched from ES5 to ES2015.
ES5 output:
```js
if (propMetadata[propName]) {
decorators.push.apply(decorators, __spread(propMetadata[propName]));
}
```
ES2015 output:
```js
if (propMetadata[propName]) {
decorators.push(...propMetadata[propName]);
}
```
The bug was not discovered in ES5 because the polyfill for the spread
operator happily accepts parameters that do not have the `iterable`
symbol:
```js
function __spread() {
for (var ar = [], i = 0; i < arguments.length; i++)
ar = ar.concat(__read(arguments[i]));
return ar;
}
```
whereas in es2015 it’ll fail since the iterable symbol is not present in
`propMetadata['toString']` which evaluates to a function.
Fixes https://github.com/angular/vscode-ng-language-service/issues/859
PR Close#38292
fd51e01335