Switch from xml.dom.minidom to xml.etree

The reason of this change (beside deleting 30 lines) is to fix pylint on Mac.
For an unknown reason, it was dying here trying to process the minidom import.

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BUG=
TEST=

Review URL: http://codereview.chromium.org/6799021

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@80770 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed