Rename file to preserve history

Change-Id: Idccde58ff6a74605ed50b7cff79f4cad21c653e2
diff --git a/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.js b/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts
similarity index 100%
rename from polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.js
rename to polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts