inspector: add inspector.waitForDebugger()

This method blocks current node process until a client sends
Runtime.runifWaitingForDebugger.

It can be useful when we need to report inspector.url() before
waiting for connection:
```
inspector.open(0, undefined, false);
fs.writeFileSync(someFileName, inspector.url());
inspector.waitForDebugger();
```

PR-URL: https://github.com/nodejs/node/pull/28453
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/api/inspector.md b/doc/api/inspector.md
index 63d2a702724..e2980a278d1 100644
--- a/doc/api/inspector.md
+++ b/doc/api/inspector.md
@@ -52,6 +52,16 @@ parameter usage.
 
 Return the URL of the active inspector, or `undefined` if there is none.
 
+## inspector.waitForDebugger()
+<!-- YAML
+added: REPLACEME
+-->
+
+Blocks until a client (existing or connected later) has sent
+`Runtime.runIfWaitingForDebugger` command.
+
+An exception will be thrown if there is no active inspector.
+
 ## Class: inspector.Session
 
 The `inspector.Session` is used for dispatching messages to the V8 inspector