Update engine revision. (#6969)

.travis.yml

@@ -6,6 +6,7 @@ addons:
       - ubuntu-toolchain-r-test # if we don't specify this, the libstdc++6 we get is the wrong version
     packages:
       - libstdc++6
+      - fonts-droid
 install:
   - gem install coveralls-lcov
   - npm install -g firebase-tools@">=3.0.4 <3.1.0"

bin/internal/engine.version

-cea5ed2b9be42a981eac762af3664e4a17d0a53f
+aecebd529935eea58182225cb76e4cff3fb1185e