This reverts commit a32f98e6.

Reason for revert:
Doesn't work when there are variables which definition includes other variables, e.g.:

'cros_download_vm': '"{cros_board}" == "amd64_generic"',

Original change's description:
> Expand variables in gclient flattened output.
> 
> Bug: 848990
> Change-Id: I0ad7e4f965973edbc5a335bd30f9cbd7b04abff2
> Reviewed-on: https://chromium-review.googlesource.com/1085996
> Reviewed-by: Michael Moss <mmoss@chromium.org>
> Reviewed-by: Aaron Gable <agable@chromium.org>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

TBR=agable@chromium.org,mmoss@chromium.org,ehmaldonado@chromium.org

Change-Id: I7e81000e92aa352e45b420845bb1dcc8572f1962
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 848990
Reviewed-on: https://chromium-review.googlesource.com/1085974Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>