Add xliffmerge to update translated files (#3991)

To apply differences of `i18n/messages.xlf` into treanslated files,
i.e. `messages.[locale].xlf` like `messages.fr.xlf` and `messages.ja.xlf`,
introduce `xliffmerge` and run it after `ng xi18n`.

aio/develop/Dockerfile

@@ -39,7 +39,7 @@ RUN curl -sL https://deb.nodesource.com/setup_11.x | bash - \
 	&& apt-get clean
 
 # Install dependencies. This will take a while.
-RUN npm install -g npm@latest gulp@4.0.2 @angular/cli@8.0.3
+RUN npm install -g npm@latest gulp@4.0.2 @angular/cli@8.0.3 ngx-i18nsupport
 
 # Set environment variable for JavaScript tests.
 ENV CHROME_BIN=/usr/bin/chromium

aio/scripts/pre-commit-i18n.sh

@@ -26,8 +26,10 @@ echo $MD5_OLD
 echo $MD5_NEW
 
 if [ $MD5_OLD != $MD5_NEW ] ; then
-  echo "i18n/messages.xlf is updated. Commit it too."
-  git add i18n/messages.xlf
+  ng xi18n --outFile ../i18n/messages.xlf
+  xliffmerge
+  echo "i18n/messages.* files are updated. Commit them too."
+  git add i18n/messages.*
 fi
 
 # Remove extracted file for check

package.json

@@ -42,7 +42,7 @@
     "check:frontend:scss": "./aio/scripts/format.sh --styles --check && ./node_modules/sass-lint/bin/sass-lint.js -c .sass-lint.yml 'src/app/frontend/**/*.scss' -v -q",
     "check:frontend:html": "./aio/scripts/format.sh --html --check",
     "check:license": "gulp check-license-headers",
-    "check:i18n": "ng xi18n --outFile ../i18n/messages.xlf",
+    "check:i18n": "ng xi18n --outFile ../i18n/messages.xlf && xliffmerge",
     "fix": "concurrently \"npm run fix:backend\" \"npm run fix:frontend\" \"npm run fix:license\" \"npm run fix:i18n\"",
     "fix:backend": "golangci-lint run -c .golangci.yml --fix src/app/backend/...",
     "fix:frontend": "concurrently \"npm run fix:frontend:ts\" \"npm run fix:frontend:scss\" \"npm run fix:frontend:html\"",
@@ -50,7 +50,7 @@
     "fix:frontend:scss": "scssfmt -r 'src/**/*.scss'",
     "fix:frontend:html": "./aio/scripts/format.sh --html",
     "fix:license": "gulp update-license-headers",
-    "fix:i18n": "ng xi18n --outFile ../i18n/messages.xlf",
+    "fix:i18n": "ng xi18n --outFile ../i18n/messages.xlf && xliffmerge",
     "clean": "rm -rf .go_workspace .tmp coverage dist npm-debug.log",
     "postversion": "node aio/scripts/version.js",
     "postinstall": "node aio/scripts/version.js && ./node_modules/protractor/bin/webdriver-manager update --gecko=false --versions.standalone=3.141.59 && curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.17.1"
@@ -78,6 +78,16 @@
       "git add"
     ]
   },
+  "xliffmergeOptions": {
+    "srcDir": "i18n",
+    "genDir": "i18n",
+    "defaultLanguage": "en",
+    "languages": [
+      "fr",
+      "ja"
+    ],
+    "beautifyOutput": true
+  },
   "dependencies": {
     "@angular/animations": "8.0.3",
     "@angular/cdk": "8.0.2",
@@ -154,6 +164,7 @@
     "lodash": "4.17.11",
     "minimatch": "3.0.4",
     "minimist": "1.2.0",
+    "ngx-i18nsupport": "^0.17.1",
     "node-gyp": "5.0.2",
     "node-sass": "4.12.0",
     "protractor": "5.4.1",