Hopefully fixes tests on Linux.

Author: ben-eb

.travis.yml

@@ -21,3 +21,4 @@ before_install:
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install cairo pango  ; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then sudo apt-get -qq update ; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then sudo apt-get install -y pkg-config libcairo2-dev libpango1.0-dev libssl-dev libjpeg62-dev libgif-dev; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then npm install canvas      ; fi