Add git-add command.
Add git_salt api.
Recompile.
Call dart api for git-salt.
Merge branch 'master' into git_add

Conflicts:
	ide/web/lib/git_salt/constants.h
	ide/web/lib/git_salt/git_command.cc
	ide/web/lib/git_salt/git_command.h
	ide/web/lib/git_salt/git_salt.cc
	ide/web/lib/git_salt/git_salt.dart
	ide/web/lib/git_salt/git_salt.h
	ide/web/lib/git_salt/git_salt_arm.nexe
	ide/web/lib/git_salt/git_salt_x86_32.nexe
	ide/web/lib/git_salt/git_salt_x86_64.nexe
Merge branch 'master' into git_add
Remove duplicate include.
Implement git-add.
Recompile.
Remove debug logs.
Recompile.
Merge pull request #3678 from dart-lang/git_add

Git add