chore(travis): don't build package for the "unit" job

Source test:unit do not need built or packaged code,
and, and tests:docs only need built code.

Author: Narretz

scripts/travis/before_build.sh

@@ -4,15 +4,26 @@ set -e
 
 yarn global add [email protected]
 
-mkdir -p $LOGS_DIR
+mkdir -p "$LOGS_DIR"
 
-if [ $JOB != "ci-checks" ]; then
+if [ "$JOB" != "ci-checks" ]; then
   echo "start_browser_provider"
   ./scripts/travis/start_browser_provider.sh
 fi
 
-if [ $JOB != "ci-checks" ]; then
+# ci-checks and unit tests do not run against the packaged code
+if [ "$JOB" != "ci-checks" ] && [ "$JOB" != "unit" ]; then
   grunt package
+fi
+
+# unit runs the docs tests too which need a built version of the code
+if [ "$JOB" = "unit" ]; then
+  grunt build
+fi
+
+# check this after the package, because at this point the browser_provider
+# has probably arrived
+if [ "$JOB" != "ci-checks" ]; then
   echo "wait_for_browser_provider"
   ./scripts/travis/wait_for_browser_provider.sh
-fi
+fi