update all frontend tests to point to precompiled fixtures

spec/javascripts/activities_spec.js.es6

spec/javascripts/behaviors/quick_submit_spec.js

spec/javascripts/behaviors/requires_input_spec.js

spec/javascripts/bootstrap_linked_tabs_spec.js.es6

spec/javascripts/dashboard_spec.js.es6

.../javascripts/environments/environment_actions_spec.js.es6

...scripts/environments/environment_external_url_spec.js.es6

spec/javascripts/environments/environment_item_spec.js.es6

...javascripts/environments/environment_rollback_spec.js.es6

spec/javascripts/environments/environment_stop_spec.js.es6

spec/javascripts/gl_dropdown_spec.js.es6

spec/javascripts/gl_field_errors_spec.js.es6

spec/javascripts/header_spec.js

spec/javascripts/issuable_spec.js.es6

spec/javascripts/issue_spec.js

spec/javascripts/labels_issue_sidebar_spec.js.es6

spec/javascripts/line_highlighter_spec.js

spec/javascripts/merge_request_spec.js

spec/javascripts/merge_request_tabs_spec.js

spec/javascripts/mini_pipeline_graph_dropdown_spec.js.es6