https://shell.cloud.google.com でF5でデバッグできます
.theia/launch.json
{
// Use IntelliSense to learn about possible attributes.
// Hover to view descriptions of existing attributes.
"version": "0.2.0",
"configurations": [
{
"type": "php",
"request": "launch",
"name": "Launch Program",
"program": "${file}"
}
]
}