Actually update .travis.yml to remove dartfmt step

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=204806724

Author: alan-knight

.travis.yml

@@ -6,7 +6,6 @@ dart:
 dart_task:
   - test: -p vm
   - test: -p firefox
-  - dartfmt
   - dartanalyzer
 
 # Only building master means that we don't run two builds for each pull request.