Investigate why guard-for-in doesn't work for all cases

We have the eslint rule

```js
'guard-for-in': 'error'
```

but it doesn't error on cases like

```js
for (var subMaterialId in materials) {
if (shaderComponent.indexOf(subMaterialId) > -1) {
return true;
}
}
```

which should actually look like:

```js
var materials = material._template.materials;
for (var subMaterialId in materials) {
if (materials.hasOwnProperty(subMaterialId)) {
if (shaderComponent.indexOf(subMaterialId) > -1) {
return true;
}
}
}
```

It seems like [`guard-for-in`](https://eslint.org/docs/rules/guard-for-in) is happy as long as there's an if statement after the for loop but it doesn't actually check with whether `hasOwnProperty` is called.

Start by reproducing the two JavaScript examples with the `guard-for-in` rule and read the linked rule documentation. Compare the rule's accepted `if` statement with the required `hasOwnProperty` guard; done means identifying why the case is accepted and documenting the needed scope of the fix.

Written by the indexing model from the issue text.