Simplify TestCompiler and avoid running dart2js_unit in too many configurations.
Simplify TestCompiler and avoid running dart2js_unit in too
many configurations.

R=ngeoffray@google.com
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com//10446059

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@8055 260f80e4-7a28-3924-810f-c04153c831b5

dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk