Rename two tests to browser_specs

- fly_out_nav_spec
- tooltip_on_truncate_spec

spec/javascripts/fly_out_nav_spec.js → spec/javascripts/fly_out_nav_browser_spec.js

+// this file can't be migrated to jest because it relies on the browser to perform integration tests:
+// (specifically getClientBoundingRect and mouse movements)
+// see: https://gitlab.com/groups/gitlab-org/-/epics/895#what-if-theres-a-karma-spec-which-is-simply-unmovable-to-jest-ie-it-is-dependent-on-a-running-browser-environment
+
 import { GlBreakpointInstance } from '@gitlab/ui/dist/utils';
 import {
   calculateTop,

spec/javascripts/vue_shared/components/tooltip_on_truncate_spec.js → spec/javascripts/vue_shared/components/tooltip_on_truncate_browser_spec.js

+// this file can't be migrated to jest because it relies on the browser to perform integration tests:
+// (specifically testing around css properties `overflow` and `white-space`)
+// see: https://gitlab.com/groups/gitlab-org/-/epics/895#what-if-theres-a-karma-spec-which-is-simply-unmovable-to-jest-ie-it-is-dependent-on-a-running-browser-environment
+
 import { mount, shallowMount } from '@vue/test-utils';
 import TooltipOnTruncate from '~/vue_shared/components/tooltip_on_truncate.vue';