Modify google analytics experiment code (#493)
Modify google analytics experiment code (#493)

* fix google analytics experiment code.

* add advanced amp-experiment with google analytics.

* add comment

* remove amp-analytics from amp-experiment. and refer to advanced page.

* change experiment key.

* replace the existing css experiment config with index-based config.

* delete advanced amp-experiment_with_google_analytics page.

* s/amp-experiment/`amp-experiment`/

* remove comment section.

* remove blank.

camelburrito/amp-by-example,camelburrito/amp-by-example,ampproject/amp-by-example,ampproject/amp-by-example,camelburrito/amp-by-example,camelburrito/amp-by-example,ampproject/amp-by-example,ampproject/amp-by-example