test: rearrange inspector headers into convention

Test guide describes a conventional layout for test headers, review
inspector tests and reorganize to follow the convention.

PR-URL: https://github.com/nodejs/node/pull/13428
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/inspector/test-inspector-debug-brk.js

@@ -1,6 +1,8 @@
 'use strict';
 const common = require('../common');
+
 common.skipIfInspectorDisabled();
+
 const assert = require('assert');
 const helper = require('./inspector-helper.js');
 

test/inspector/test-inspector-ip-detection.js

@@ -1,5 +1,6 @@
 'use strict';
 const common = require('../common');
+
 common.skipIfInspectorDisabled();
 
 const assert = require('assert');

test/inspector/test-inspector-port-zero-cluster.js

@@ -1,8 +1,9 @@
 // Flags: --inspect=0
 'use strict';
-
 const common = require('../common');
+
 common.skipIfInspectorDisabled();
+
 const assert = require('assert');
 const cluster = require('cluster');
 

test/inspector/test-inspector-port-zero.js

@@ -1,7 +1,8 @@
 'use strict';
-
 const { mustCall, skipIfInspectorDisabled } = require('../common');
+
 skipIfInspectorDisabled();
+
 const assert = require('assert');
 const { URL } = require('url');
 const { spawn } = require('child_process');

test/inspector/test-inspector-stops-no-file.js

@@ -1,5 +1,6 @@
 'use strict';
 require('../common');
+
 const spawn = require('child_process').spawn;
 
 const child = spawn(process.execPath,

test/inspector/test-inspector.js

@@ -1,6 +1,8 @@
 'use strict';
 const common = require('../common');
+
 common.skipIfInspectorDisabled();
+
 const assert = require('assert');
 const helper = require('./inspector-helper.js');
 

test/parallel/test-cluster-inspector-debug-port.js

@@ -1,7 +1,9 @@
 'use strict';
 // Flags: --inspect={PORT}
 const common = require('../common');
+
 common.skipIfInspectorDisabled();
+
 const assert = require('assert');
 const cluster = require('cluster');
 const debuggerPort = common.PORT;

test/parallel/test-inspector-invalid-args.js

@@ -1,11 +1,12 @@
 'use strict';
+const common = require('../common');
+
+common.skipIfInspectorDisabled();
+
 const assert = require('assert');
 const execFile = require('child_process').execFile;
 const path = require('path');
 
-const common = require('../common');
-common.skipIfInspectorDisabled();
-
 const mainScript = path.join(common.fixturesDir, 'loop.js');
 const expected =
   '`node --debug` and `node --debug-brk` are invalid. ' +