Enhance sparkException class.
review comments
Merge pull request #2045 from dinhviethoa/1795-navigation-history

Navigation history tracks the location we jumped from
Deploy only master to nightly
Merge pull request #2052 from dinhviethoa/deploy

Deploy only master to nightly
review comments
Merge pull request #2047 from devoncarew/devocarew_file_icons

Devocarew file icons
add a missing method
Merge pull request #2055 from devoncarew/devoncarew_missing_impl

add a missing method
Force deliver change events to button.
remove unused code.
disable dart2js tests on drone
script fix
Merge pull request #2003 from dart-lang/umop-linking-progress_indicator

Linking progress indicator for long operations
fixed comments.
Merge pull request #1971 from dart-lang/clone_cancel

Make git clone cancellable
Merge pull request #2057 from devoncarew/devoncarew_disable_drone

Devoncarew disable drone
Cosmetic review fix

Per https://github.com/dart-lang/spark/pull/2003#discussion_r12984688
Show error on cloning a with empty projectName.
message.