minor tweaks to run.sh.
 - the new 'dartanalyzer' doesn't create the work directory
 - minor changes in printing and grouping messages in the output

Review URL: https://chromiumcodereview.appspot.com//13877011
Revert change on clearning directories until we fix dependency between
render_tests and html5_util_test

Review URL: https://chromiumcodereview.appspot.com//14053017
fix KeyEvent, it only worked if you import dart:html yourself

Review URL: https://chromiumcodereview.appspot.com//14024011