material properties only work with direct assignment (`=`) but not with compound-assignment (e.g.: `*=`)

**Describe the bug**
`clipSpaceTransform` won't compile at all in `matc` for a `vertexDomain:device` shader ([docs](https://google.github.io/filament/Materials.html#materialdefinitions/vertexblock/materialvertexinputs), [previous discussion](https://github.com/google/filament/issues/1685#issuecomment-583622797)).

**To Reproduce**
1. `git clone git@github.com:google/filament.git`
2. `./build.sh release matc`
3. Minimal shader `test_direct_pixels.mat`:
```
material {
name: TestDirectPixels,
parameters: [
],
requires : [
uv0
],
blending : transparent,
vertexDomain : device,
shadingModel : unlit
}

vertex {
void materialVertex(inout MaterialVertexInputs material) {
material.clipSpaceTransform *= 0.3;
}
}

fragment {
void material(inout MaterialInputs material) {
prepareMaterial(material);
vec2 uv = getUV0();
material.baseColor = float4(0.0, 0.1, 0.4, 0.4);
}
}

```
5. ```./out/cmake-release/tools/matc/matc --api=metal --platform=mobile --output=./test_direct_pixels.filamat ./test_direct_pixels.mat```
6. `matc` compilation fails:
```
➜ filament git:(main) ✗ ./out/cmake-release/tools/matc/matc --api=metal --platform=mobile --output=./test_direct_pixels.filamat ./test_direct_pixels.mat
ERROR: Unable to parse vertex shader
ERROR: test_direct_pixels.mat:15: 'clipSpaceTransform' : no such field in structure 'material'
ERROR: test_direct_pixels.mat:15: '' : compilation terminated
ERROR: 2 compilation errors. No code generated.

Could not compile material ./test_direct_pixels.mat
```

**Expected behavior**
`matc` compilation should work, though it may have broken [here](https://github.com/google/filament/blob/af2ecf201f5b9116cba84d0c6ca0593fae1d52f1/RELEASE_NOTES.md?plain=1#L421)?

**Screenshots**
N/A

**Logs**
(see Step 6 above)

**Desktop (please complete the following information):**
- OS: macOS
- GPU: MacBook Pro Nov 2023
- Backend: Metal

**Smartphone (please complete the following information):**
- Device: N/A (offline `matc`)
- OS: N/A (offline `matc`)

**Additional context**
I'm looking to create a 2D quad, with 256 instances, and do efficient vertex transforms on the GPU.

Thanks as always team!