DAS insights: use continue instead of return when crashed plugin

When I forked this page for a _list_ of plugin isolates, I neglected
to convert this 'return' into a 'continue'.

Change-Id: I61868a83a379c910b3381134c165b6ddb4f45ff1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/450100
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

Author: srawlins

pkg/analysis_server/lib/src/status/pages/plugins_page.dart

@@ -59,7 +59,7 @@ class PluginsPage extends DiagnosticPageWithNav {
             'starting).',
           );
         }
-        return;
+        continue;
       }
 
       p('Associated contexts:');