Fix localization of developer-resources

The console was showing all kinds of errors for this panel.
There were multiple issues:
- The registration call was using `*.js` rather than `*.ts`
- The meta file used `ls` instead of `i18nString`

R=petermarshall@chromium.org

Change-Id: I6063ce357ced424fcbc3d224c8e67ee97ebd279b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2635665
Commit-Queue: Tim van der Lippe <tvanderlippe@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 04236f2..adc190a 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -349,7 +349,7 @@
     devtools_front_end = input_api.os_path.join(devtools_root, 'front_end')
     affected_front_end_files = _getAffectedFiles(input_api,
                                                  [devtools_front_end], ['D'],
-                                                 ['.js'])
+                                                 ['.js', '.ts'])
     if len(affected_front_end_files) == 0:
         return [
             output_api.PresubmitNotifyResult(