[Gradle, JS] Consider custom launcher's base

^KT-41475 fixed

libraries/tools/kotlin-test-js-runner/src/DebugConfigurator.js

@@ -25,11 +25,7 @@ export function configureBrowsers(config) {
 }
 
 function isDebuggableBrowser(browserName, config) {
-    if ([
-        'ChromeHeadless',
-        'ChromeCanaryHeadless',
-        'ChromiumHeadless'
-    ].includes(browserName)) {
+    if (isDebuggableBrowserName(browserName)) {
         return true
     }
 
@@ -43,6 +39,10 @@ function isDebuggableBrowser(browserName, config) {
         return false;
     }
 
+    if (isDebuggableBrowserName(customLauncher.base)) {
+        return true
+    }
+
     const flags = customLauncher.flags;
     if (!Array.isArray(flags)) {
         return false;
@@ -63,6 +63,14 @@ function isDebuggableBrowser(browserName, config) {
     return true;
 }
 
+function isDebuggableBrowserName(browserName) {
+    return [
+        'ChromeHeadless',
+        'ChromeCanaryHeadless',
+        'ChromiumHeadless'
+    ].includes(browserName);
+}
+
 export function fixMochaTimeout(config) {
     let client = config.client;
     if (typeof client === 'undefined') {