Revert of Make landmines work on local builds too

Revert of Make landmines work on local builds too (patchset #3 of https://codereview.chromium.org/457003004/)

Reason for revert:
Apparently this requires win_toolchain.json to exist, but I'm not sure how it's supposed to get there (as seen on a clobber build):


Traceback (most recent call last):
  File "src/build/landmines.py", line 132, in <module>
    sys.exit(main())
  File "src/build/landmines.py", line 119, in main
    gyp_environment.SetEnvironment()
  File "C:\b\build\slave\win_trunk\build\src\build\gyp_environment.py", line 33, in SetEnvironment
    vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
  File "C:\b\build\slave\win_trunk\build\src\build\vs_toolchain.py", line 33, in SetEnvironmentAndGetRuntimeDllDirs
    with open(json_data_file, 'r') as tempf:
IOError: [Errno 2] No such file or directory: 'C:\\b\\build\\slave\\win_trunk\\build\\src\\build\\win_toolchain.json'

Original issue's description:
> Make landmines work on local builds too
> 
> Moves (some of) gyp environment setup out of gyp_chromium into separate
> module, and shares that between gyp_chromium and landmines.py.
> 
> landmines.py is added as the first entry in DEPS hooks so that it can
> clobber the entire build directory before running other hooks that
> extract/generate into the build dir.
> 
> R=iannucci@chromium.org
> BUG=400011
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289099

TBR=scottmg@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=400011
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289158

[iannucci, 2014-08-13 01:59:58]

Created Revert of Make landmines work on local builds too

[commit-bot: I haz the power, 2014-08-13 02:02:47]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/iannucci@chromium.org/469623002/1

[commit-bot: I haz the power, 2014-08-13 02:07:37]

Change committed as 289158

[scottmg, 2014-08-13 02:44:03]

On 2014/08/13 02:07:37, I haz the power (commit-bot) wrote:
> Change committed as 289158

Bah. Thanks.

[scottmg, 2014-08-13 02:44:09]

On 2014/08/13 02:44:03, scottmg wrote:
> On 2014/08/13 02:07:37, I haz the power (commit-bot) wrote:
> > Change committed as 289158
> 
> Bah. Thanks.

er, lgtm.