### 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)

keyword_completion_context = CF_BLOCK;
#endif 
			err = _parse_block(block, p_function_info, true, true, true);
			if (err != OK) {
				return err;
			}
		} else if (tk.type == TK_CF_RETURN) {
			
			BlockNode *b = p_block;
			while (b && !b->parent_function) {
				b = b->parent_block;
			}
			if (!b) {
				_set_parsing_error();
				return ERR_BUG;
			}
			if (b->parent_function && p_function_info.main_function) {
				_set_error(vformat(RTR("Using '%s' in the '%s' processor function is incorrect."), "return", b->parent_function->name));
				return ERR_PARSE_ERROR;
			}
			String return_struct_name = String(b->parent_function->return_struct_name);
			String array_size_string;
			if (b->parent_function->return_array_size > 0) {
				array_size_string = "[" + itos(b->parent_function->return_array_size) + "]";
			}
			ControlFlowNode *flow = alloc_node<ControlFlowNode>();
			flow->flow_op = FLOW_OP_RETURN;
			pos = _get_tkpos();
			tk = _get_token();
			if (tk.type == TK_SEMICOLON) {