tests(i18n): update canonical locale test for node 12.6 (GoogleChrome#9396)

Author: brendankenny

.travis.yml

@@ -6,7 +6,7 @@ branches:
 matrix:
   include:
     - node_js: "10"
-    - node_js: "11"
+    - node_js: "12"
       if: head_branch IS blank AND branch = master
 dist: trusty
 cache:

lighthouse-core/test/lib/i18n/locales-test.js

@@ -18,13 +18,14 @@ describe('locales', () => {
     const deprecatedCodes = {
       in: 'id',
       iw: 'he',
+      mo: 'ro',
     };
 
     for (const locale of Object.keys(locales)) {
       const canonicalLocale = Intl.getCanonicalLocales(locale)[0];
       const substitute = deprecatedCodes[locale];
       assert.ok(locale === canonicalLocale || substitute === canonicalLocale,
-          `locale code '${locale}' not canonical`);
+        `locale code '${locale}' not canonical ('${canonicalLocale}' found instead)`);
     }
 
     // Deprecation subsitutes should be removed from the test if no longer used.