Transition to ExceptionState in core/workers

TBR=abarth
BUG=252233
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/19540021

git-svn-id: svn://svn.chromium.org/blink/trunk@154594 bbb929c8-8fbe-4397-9dbb-9b2b20218538