Revert "Replaces debug with phpdbg for faster test coverage report generation."

This reverts commit ccbf22a.

Author: dsposito

.travis.yml

@@ -13,12 +13,11 @@ install:
 before_script:
   - composer self-update
   - composer install --dev --no-interaction
-  - phpenv config-rm xdebug.ini
   - mkdir -p build/logs
 
 # Run tests and generate test coverage report.
 script:
-  - phpdbg -qrr phpunit -d api_key=$API_KEY --coverage-clover build/logs/clover.xml
+  - phpunit -d api_key=$API_KEY --coverage-clover build/logs/clover.xml
 
 # Submit test coverage report to Coveralls.
 after_success: