chromium: Correct tools path in blink_idl_parser.

This is because of our symlink mess, as Chromium's build support scripts
are trying to resolve everything based on absolute paths and we split
off the bundled sources from the main derivation.

Yes, I'm refering to this as a mess, because in the end, we're going to
patch up the gyp files and use references someday.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
chromium: Propagate browser's meta to the wrapper.

We obviously don't want the Hydra job of nixpkgs to fail, so we need to
make sure that we have a proper meta attribute on the outermost
derivation.

For builds based on the Chromium source tree (like for example libcef),
we can still move the wrapper elsewhere when we need it.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
chromium: Revert back to copying bundled sources.

I'm giving up on this after several attempts to correctly unbundle the
largest part, namely Google's WebKit fork Blink. Right now it's so much
tied into the Chromium source it's going to be fairly hard to do if
you're not working full time on it.

Also, the intermediate steps needed to do this properly would introduce
uneccesary complexity on our side, so we really need to finish this
without leaving it in the "messy" state in order to not make Chromium
even more difficult to maintain than it is already.

However, anyone who wants to proceed on this messy step is free to
revert this commit and continue doing so. In my case I'm going to try
again once https://crbug.com/239107 and https://crbug.com/239181 are
fixed in _stable_ (I don't want to introduce *lots* of conditionals on
the version either).

Signed-off-by: aszlig <aszlig@redmoonstudios.org>