Hook up new rc.py.

Two advantages:
* lets ninja track dependencies on resources referenced
  from .rc files
* allows building targets that use .rc files when
  cross-compiling chrome/win on non-Win hosts, e.g.
  gfx_unittests can now build on linux

Since we now get deps right automatically, remove a few manually-added
deps on .ico files.

Bug: 132660,774193
Cq-Include-Trybots: master.tryserver.chromium.win:win10_chromium_x64_rel_ng
Change-Id: Ia23ec5cba2bb06146650c40acf5b7754bbfe9a99
Reviewed-on: https://chromium-review.googlesource.com/729536
Reviewed-by: Will Harris <wfh@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510532}
7 files changed