Revert revision 41812 "Let docgen detect a dart-sdk directory that's differently named"

Revert revision 41812 "Let docgen detect a dart-sdk directory that's differently named"

The vm build is incremental, and on bleeding edge the revision number is part of the version number.
So if a cl lands that triggers a rebuild of the api docs - but not of the vm, the check for vmVersion.startsWith(version) will report false.

This is exactly what happened here:
http://build.chromium.org/p/client.dart/builders/analyzer_experimental-linux-release-be/builds/400

The change from sgjesse@ : https://code.google.com/p/dart/source/detail?r=41821
Triggered a rebuild of the api docs, but the vm remained unchanged with a version of:
1.8.0-edge.41820
The version of the build was:
1.8.0-edge.41821

Committed: https://code.google.com/p/dart/source/detail?r=41824

[ricow1, 2014-11-19 09:26:53]

tbr

[ricow1, 2014-11-19 09:27:09]

Committed patchset #1 (id:1) manually as r41824 (presubmit successful).

[Søren Gjesse, 2014-11-19 10:36:21]

lgtm

[Alan Knight, 2014-11-19 18:50:39]

Sorry about that.