add --dryRun flag to dm

BUG=2294
R=mtklein@google.com

Author: humper@google.com

Review URL: https://codereview.chromium.org/305963007

git-svn-id: http://skia.googlecode.com/svn/trunk@14999 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed