Bump bower from 1.8.2 to 1.8.4 in /build

Bumps [bower](https://github.com/bower/bower) from 1.8.2 to 1.8.4.
- [Release notes](https://github.com/bower/bower/releases)
- [Changelog](https://github.com/bower/bower/blob/master/CHANGELOG.md)
- [Commits](bower/bower@v1.8.2...v1.8.4)

Signed-off-by: dependabot[bot] <support@dependabot.com>

build/package.json

@@ -12,7 +12,7 @@
   "dependencies": {},
   "devDependencies": {
     "jasmine-core": "^2.99.1",
-    "bower": "~1.8.0",
+    "bower": "~1.8.4",
     "handlebars": "^4.0.5",
     "jasmine-sinon": "^0.4.0",
     "sinon": "^2.0.0",

build/yarn.lock

@@ -263,7 +263,7 @@ boom@5.x.x:
   dependencies:
     hoek "4.x.x"
 
-bower@~1.8.0:
+bower@~1.8.4:
   version "1.8.4"
   resolved "https://registry.yarnpkg.com/bower/-/bower-1.8.4.tgz#e7876a076deb8137f7d06525dc5e8c66db82f28a"