Update webpages_playback.py to use the new Golang impl of WPRs

NoTry: true
Bug: skia:6901
Change-Id: I1a0dc706f9494c261c2f609df81a37cc60970fdd
Reviewed-on: https://skia-review.googlesource.com/30060
Commit-Queue: Ravi Mistry <rmistry@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
1 file changed