Build/Test tools: Don't install PHPUnit on the `travis:js` builds. Saves a couple of minutes of build time.

See #40100


git-svn-id: https://develop.svn.wordpress.org/trunk@40271 602fd350-edb4-49c9-b593-d223f7449a82

.travis.yml

@@ -65,24 +65,26 @@ before_script:
   fi
 - |
   # Install the specified version of PHPUnit depending on the PHP version:
-  case "$TRAVIS_PHP_VERSION" in
-    7.1|7.0|hhvm|nightly)
-      echo "Using PHPUnit 5.7"
-      composer global require "phpunit/phpunit=5.7.*"
-      ;;
-    5.6|5.5|5.4|5.3)
-      echo "Using PHPUnit 4.8"
-      composer global require "phpunit/phpunit=4.8.*"
-      ;;
-    5.2)
-      # Do nothing, use default PHPUnit 3.6.x
-      echo "Using default PHPUnit, hopefully 3.6"
-      ;;
-    *)
-      echo "No PHPUnit version handling for PHP version $TRAVIS_PHP_VERSION"
-      exit 1
-      ;;
-  esac
+  if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
+    case "$TRAVIS_PHP_VERSION" in
+      7.1|7.0|hhvm|nightly)
+        echo "Using PHPUnit 5.7"
+        composer global require "phpunit/phpunit=5.7.*"
+        ;;
+      5.6|5.5|5.4|5.3)
+        echo "Using PHPUnit 4.8"
+        composer global require "phpunit/phpunit=4.8.*"
+        ;;
+      5.2)
+        # Do nothing, use default PHPUnit 3.6.x
+        echo "Using default PHPUnit, hopefully 3.6"
+        ;;
+      *)
+        echo "No PHPUnit version handling for PHP version $TRAVIS_PHP_VERSION"
+        exit 1
+        ;;
+    esac
+  fi
 - npm --version
 - node --version
 - nvm install 6.9.1