Fix issue with the inspector panel in the Dart Debug Extension (#2242)

Author: elliette

dwds/debug_extension_mv3/web/utils.dart

@@ -143,6 +143,7 @@ String addQueryParameters(
 }) {
   final originalUri = Uri.parse(uri);
   final newUri = originalUri.replace(
+    path: '', // Replace the /debugger path so that the inspector url works.
     queryParameters: {
       ...originalUri.queryParameters,
       ...queryParameters,

dwds/test/puppeteer/extension_common.dart

@@ -694,7 +694,8 @@ void testAll({
           // origin, and being able to connect to the embedded Dart app.
           // See https://github.com/dart-lang/webdev/issues/1779
 
-          test('The Dart DevTools IFRAME has the correct query parameters',
+          test(
+              'The Dart DevTools IFRAME has the correct query parameters and path',
               () async {
             final chromeDevToolsPage = await getChromeDevToolsPage(browser);
             // There are no hooks for when a panel is added to Chrome DevTools,
@@ -736,6 +737,7 @@ void testAll({
               queryParameters,
               containsPair('backgroundColor', isNotEmpty),
             );
+            expect(uri.path, equals('/'));
           });
 
           test('Trying to debug a page with multiple Dart apps shows warning',