This commit changes Travis configuration to only install Chrome and Nginx in the e2e tests build job, which is the only one that requires those packages. This change should save a little bit of time in the Travis build as before Travis was installing Chrome and Nginx in all the jobs.
PR https://github.com/woocommerce/woocommerce/pull/23082 made some changes to the Travis configuration and one of those changes broke the PHPCS when running inside Travis with the following error:
```
ERROR: Referenced sniff "WooCommerce-Core" does not exist
```
For example: https://travis-ci.org/woocommerce/woocommerce/jobs/509471213#L659
This problem went unnoticed during the PR review as no PHP file was modified in it and thus there was no file for PHPCS to check.
This commit fixes the error above by installing the Composer package `woocommerce/woocommerce-sniffs` which is the package that provides `WooCommerce-Core` sniffs and which installs `wp-coding-standards/wpcs` as one of its requirements. I couldn't find an easy way to make this work installing `woocommerce/woocommerce-sniffs` globally so that is why this commit also removes the `global` parameter when calling composer.
Changing the private class methods to protected allows extending the class to work with the built-in functionality.
The desired effect - removing the "Shop" crumb - was not possible with the few filters available interspersed in this class.
After much hair-pulling over the simple task of excluding one breadcrumb and the stubborn refusal to copy-pasta the entire class into my theme, I choose to extend the WC_Breadcrumb class to override the already-public add_crumb method. Without access to the other methods on the class, this was futile.
There are several asks around the web for removing or updating the breadcrumbs. The accepted answer to these appears to be to "just hide it with CSS" which is a poor workaround.