build(): Add a dartanalyzer run to Travis. It is required.

scripts/ci/build-and-test.sh

@@ -18,8 +18,7 @@ is_dart && pub install
 
 wait_for_tunnel
 if is_dart; then
-  # npm run dartanalyzer
-  echo 'TODO(hans): Implement dartanalyzer'
+  npm run dartanalyzer
 else
   karma start test/karma.conf.js --single-run --no-auto-watch --reporters='dots'
 fi

scripts/ci/dart_analyzer.ts

@@ -5,8 +5,13 @@ import {detect} from '../../tools/build/dart';
 const command = detect()['ANALYZER'];
 
 analyze('dist/dart', command, true)
-  .then(() => {
+  .then((err) => {
+    if (err) {
+      throw err;
+    }
     console.log('Done.');
-  }, (err) => {
+  })
+  .catch((err) => {
     console.error('Error:', err);
+    process.exit(1);
   });