Use case

• I want to be able to have a different l10n.yaml file for when I deploy to the web and on an Android phone. (Use different l10n.yaml when developing for mobile vs deploying the web version gallery#357)
• I want to have a different analysis_options.yaml file depending on the environment, so that in tests I can be less strict compared to when developing. (See We should ignore deprecation warnings in flutter/tests gallery#356) This might be a Dart issue rather than a Flutter issue.

Proposal

Via Environment variables let us set the path to the different yaml files.

L10N_PATH=web/l10n.yaml flutter build web
ANALYSIS_OPTIONS_PATH=tests/analysis_options.yaml flutter analyze