deps: drop @atlaskit/layer-manager dependency

We no longer need it since Rect 16 takes care of passing the context around.
It's also deprecated: https://atlaskit.atlassian.com/packages/core/layer-manager

package-lock.json

         "react-scrolllock": "^3.0.2"
       }
     },
-    "@atlaskit/layer-manager": {
-      "version": "5.0.19",
-      "resolved": "https://registry.npmjs.org/@atlaskit/layer-manager/-/layer-manager-5.0.19.tgz",
-      "integrity": "sha512-2NvSNEERS9uW/oExF7ltj/h8akJvJRJnhEleKGx1JXqnbCUwQHtGkiP+06cX9JriGnhPEySt26dfQS5dAA0sKg==",
-      "requires": {
-        "@babel/runtime": "^7.0.0",
-        "prop-types": "^15.5.10",
-        "react-focus-lock": "^1.11.3",
-        "react-scrolllock": "^3.0.2",
-        "react-transition-group": "^2.2.1"
-      }
-    },
     "@atlaskit/lozenge": {
       "version": "6.2.4",
       "resolved": "https://registry.npmjs.org/@atlaskit/lozenge/-/lozenge-6.2.4.tgz",

package.json

     "@atlaskit/icon": "15.0.3",
     "@atlaskit/inline-dialog": "5.3.0",
     "@atlaskit/inline-message": "7.0.10",
-    "@atlaskit/layer-manager": "5.0.19",
     "@atlaskit/lozenge": "6.2.4",
     "@atlaskit/modal-dialog": "7.1.2",
     "@atlaskit/multi-select": "11.0.13",

react/features/base/dialog/components/web/StatelessDialog.js

 // @flow
 
 import Button, { ButtonGroup } from '@atlaskit/button';
-import { withContextFromProps } from '@atlaskit/layer-manager';
 import Modal, { ModalFooter } from '@atlaskit/modal-dialog';
 import _ from 'lodash';
 import PropTypes from 'prop-types';
     width: string
 };
 
-/**
- * ContexTypes is used as a workaround for Atlaskit's modal being displayed
- * outside of the normal App hierarchy, thereby losing context. ContextType
- * is responsible for taking its props and passing them into children.
- *
- * @type {ReactElement}
- */
-const ContextProvider = withContextFromProps({
-    i18n: PropTypes.object
-});
-
 /**
  * Web dialog that uses atlaskit modal-dialog to display dialogs.
  */
                 onDialogDismissed = { this._onDialogDismissed }
                 shouldCloseOnEscapePress = { true }
                 width = { width || 'medium' }>
-                {
-
-                    /**
-                     * Wrapping the contents of {@link Modal} with
-                     * {@link ContextProvider} is a workaround for the
-                     * i18n context becoming undefined as modal gets rendered
-                     * outside of the normal react app context.
-                     */
-                }
-                <ContextProvider i18n = { this.props.i18n }>
-                    <div
-                        onKeyDown = { this._onKeyDown }
-                        ref = { this._setDialogElement }>
-                        <form
-                            className = 'modal-dialog-form'
-                            id = 'modal-dialog-form'
-                            onSubmit = { this._onSubmit }>
-                            { children }
-                        </form>
-                    </div>
-                </ContextProvider>
+                <div
+                    onKeyDown = { this._onKeyDown }
+                    ref = { this._setDialogElement }>
+                    <form
+                        className = 'modal-dialog-form'
+                        id = 'modal-dialog-form'
+                        onSubmit = { this._onSubmit }>
+                        { children }
+                    </form>
+                </div>
             </Modal>
         );
     }