To avoid using debugging context and debugger-script.js on inspector side we can move SetScriptSource call to v8::internal::Debug. Theoretically we can move live edit implementation to native completely but since it will be reimplemented it looks redundant.

R=yangguo@chromium.org,jgruber@chromium.org

Bug: chromium:652939
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Id09492c2d2a93efbde429c9cc1bc181d5fdda19b
Reviewed-on: https://chromium-review.googlesource.com/590736
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46985}