### 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)

switch (p_type) {
		case TYPE_STRUCT: {
			_set_error(RTR("The precision modifier cannot be used on structs."));
			return FAILED;
		} break;
		case TYPE_BOOL:
		case TYPE_BVEC2:
		case TYPE_BVEC3:
		case TYPE_BVEC4: {
			_set_error(RTR("The precision modifier cannot be used on boolean types."));
			return FAILED;
		} break;
		default:
			break;
	}
	return OK;
}
Error ShaderLanguage::_parse_shader(const HashMap<StringName, FunctionInfo> &p_functions, const Vector<ModeInfo> &p_render_modes, const HashSet<String> &p_shader_types) {
	Token tk;
	TkPos prev_pos;
	Token next;
	if (!is_shader_inc) {
#ifdef DEBUG_ENABLED
		keyword_completion_context = CF_SHADER_TYPE;
#endif 
		tk = _get_token();
		if (tk.type != TK_SHADER_TYPE) {
			_set_error(vformat(RTR("Expected '%s' at the beginning of shader. Valid types are: %s."), "shader_type", _get_shader_type_list(p_shader_types)));
			return ERR_PARSE_ERROR;
		}