[skiaserver] Start loading html/css/js from https://debugger-assets.skia.org.

Also clean up quoting and fix a hard-coded URL to https://debugger.skia.org.

Bug: skia:
Change-Id: I31283f3769c81a138d82c03214f005c7fb82c5b2
Reviewed-on: https://skia-review.googlesource.com/129164
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
1 file changed