### Godot version

4.0.beta16

### System information

Windows 10 Pro x64, GLES3, RTX 3080 Ti (528.02)

### Issue description

In Compatibility/GLES3 back-end, shaders which use a uniform to get the normal roughness buffer cannot compile. For example, the shader:
```glsl
shader_type spatial;

uniform sampler2D normal_roughness_texture : hint_normal_roughness_texture;

void fragment() {
    vec4 sample = texture(normal_roughness_texture, UV);
}
```
results in an error in the output:
```
  drivers/gles3/shader_gles3.cpp:242 - SceneShaderGLES3: Fragment shader compilation failed:
  0(890) : error C1503: undefined variable "normal_roughness_buffer"
  
  drivers/gles3/shader_gles3.cpp:342 - Method/function failed.
```

If I switch over to the Mobile or Forward+ backends, there is no shader compilation error.

### Steps to reproduce

Open the attached reproduction in the 4.0.beta16 editor.

When the scene is opened, the error is produced automatically:
1. Open `scene.tscn`
2. Open Output to review error

When the scene is saved with any changes made to the shader, the same error is also produced:
1. Open `scene.tscn`
2. Open `example.gdshader` in the shader editor.
3. Make a compile-able change to the shader.
4. Save the scene
5. Open Output to review the error

### Minimal reproduction project

[NormalRoughnessTexture_GLES3_Error.zip](https://github.com/godotengine/godot/files/10534253/NormalRoughnessTexture_GLES3_Error.zip)

}
						mn->index_expression = index_expression;
					} else {
						_set_tkpos(prev_pos);
					}
				}
				expr = mn;
#ifdef DEBUG_ENABLED
				keyword_completion_context = prev_keyword_completion_context;
#endif
				
				
				
				/*} else if (tk.type==TK_BRACKET_OPEN) {
				
				//subindexing has priority over any operator
				
	*/
			} else if (tk.type == TK_BRACKET_OPEN) {
				Node *index = _parse_and_reduce_expression(p_block, p_function_info);
				if (!index) {
					return nullptr;
				}
				if (index->get_array_size() != 0 || (index->get_datatype() != TYPE_INT && index->get_datatype() != TYPE_UINT)) {
					_set_error(RTR("Only integer expressions are allowed for indexing."));
					return nullptr;
				}
				DataType member_type = TYPE_VOID;
				String member_struct_name;
				if (expr->get_array_size() > 0) {