Shader with a variable called `new` will fail when running with Metal

Shader with a variable called `new` will fail when running with Metal because Metal is based on C++14 and `new` is a keyword even though it is restricted.

See https://developer.apple.com/metal/Metal-Shading-Language-Specification.pdf

```
1.4.4
Restrictions
The following C++14 features are not available in Metal (section numbers in this list refer to the
C++14 Specification):
...
• new and delete operators (sections 5.3.4 and 5.3.5)
...
```