Most methods on runtime agent are available when agent is disabled, we compile
injected-script lazily and should not invalidate it on runtime.disable since it
will invalidate all related objectIds.

R=dgozman@chromium.org

Bug: none
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I86f3c5d6908862cd4c0847c433f35a6d83c6396b
Reviewed-on: https://chromium-review.googlesource.com/607153
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47265}