## Objective
Get rid of a redundant Cargo feature flag.
## Solution
Use the built-in `target_abi = "sim"` instead of a custom Cargo feature
flag, which is set for the iOS (and visionOS and tvOS) simulator. This
has been stable since Rust 1.78.
In the future, some of this may become redundant if Wgpu implements
proper supper for the iOS Simulator:
https://github.com/gfx-rs/wgpu/issues/7057
CC @mockersf who implemented [the original
fix](https://github.com/bevyengine/bevy/pull/10178).
## Testing
- Open mobile example in Xcode.
- Launch the simulator.
- See that no errors are emitted.
- Remove the code cfg-guarded behind `target_abi = "sim"`.
- See that an error now happens.
(I haven't actually performed these steps on the latest `main`, because
I'm hitting an unrelated error (EDIT: It was
https://github.com/bevyengine/bevy/pull/17637). But tested it on
0.15.0).
---
## Migration Guide
> If you're using a project that builds upon the mobile example, remove
the `ios_simulator` feature from your `Cargo.toml` (Bevy now handles
this internally).
94deca81bf