Revert of xp: copy dbghelp.dll to output dir and have base.isolate use it there

Revert of xp: copy dbghelp.dll to output dir and have base.isolate use it there (patchset #6 id:100001 of https://codereview.chromium.org/951083003/)

Reason for revert:
some blink waterfall failing for reasons unclear. dependency on base.isolate without depending on base maybe?

Original issue's description:
> xp: copy dbghelp.dll to output dir and have base.isolate use it there
>
> Previous CL https://codereview.chromium.org/943933005 didn't work properly
> because the dll wasn't in the same directory as the binary, so it was still
> loading the system dbghelp.dll. See details in 460506.
>
> Copies dbghelp.dll to the output dir, and has the isolate file point at that.
>
> Re-enable tests that were failing due to dbghelp hanging.
>
> XP test run here: https://chromium-swarm.appspot.com/user/task/25d5bc17b6dddc10
>
> BUG=460506, 461160
>
> Committed: https://crrev.com/09acc50cfadc6aa38db23ddadec134410ec968c0
> Cr-Commit-Position: refs/heads/master@{#317868}

TBR=cpu@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=460506, 461160
Committed: https://crrev.com/9b8a0877ef9a56c31dfd37cc4c335dfd39d51e96
Cr-Commit-Position: refs/heads/master@{#317900}

[scottmg, 2015-02-24 22:21:12]

Created Revert of xp: copy dbghelp.dll to output dir and have base.isolate use
it there

[commit-bot: I haz the power, 2015-02-24 22:22:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/954003002/1

[commit-bot: I haz the power, 2015-02-24 22:23:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-24 22:24:42]

Patchset 1 (id:??) landed as
https://crrev.com/9b8a0877ef9a56c31dfd37cc4c335dfd39d51e96
Cr-Commit-Position: refs/heads/master@{#317900}