fiddle: use sstream for text, code cleanup

Change-Id: I57cbb33688f1cd97a2172160d06e4bdd468880d1
Reviewed-on: https://skia-review.googlesource.com/8489
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
1 file changed