Start again deleting %TEMP% on Windows.
Start again deleting %TEMP% on Windows.

Be smarter about deleting; try to delete item one by one and skip anything that
fails silently.

Currently restricted to bot 'Windows Swarm Tests' on chromium.swarm, will remove
the condition once it's verified to work.

Include workaround for bug 449511.

R=stip@chromium.org
BUG=489526,449511

Review URL: https://codereview.chromium.org/1145973008

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@295496 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build