Merge pull request #52 from DrMarcII/master

More chrome extension APIs.
Adding extension test harness
Adding build task for harness
Adding build tasks
cleaned up logging and comments
applying changes from test folder
Removing harness_extension.dart
disable failing test for now
Merge pull request #55 from financeCoding/master_merged

Extension test harness
minor cleanup for how runtime fields are accessed
one more reference
Merge pull request #56 from dart-gde/fixes

lgtm