Revert "[Dark] Add build flag and experiment flag"

This reverts commit 8ef8c364dc0648b4905c4f9cfdf053e4279a47fb.

Reason for revert: Cause of crbug.com/920401

Original change's description:
> [Dark] Add build flag and experiment flag
> 
> This patch adds a build flag and an experiment flag for the dark mode
> experiment. It will exclude the night- resources in the build for now.
> 
> Bug: 919684
> Change-Id: I16f7dc0b076268863f6ec537d4ee41af124366df
> Reviewed-on: https://chromium-review.googlesource.com/c/1399457
> Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
> Reviewed-by: Theresa <twellington@chromium.org>
> Commit-Queue: Becky Zhou <huayinz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#621172}

TBR=ellyjones@chromium.org,twellington@chromium.org,huayinz@chromium.org

Change-Id: I622fee8c24bf12771a8353d18970a5a77021999b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 919684, 920401
Reviewed-on: https://chromium-review.googlesource.com/c/1403986
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621349}
17 files changed