ref: move all prop type declaration to flow

For the most part the changes are taking the "static propTypes" declaration off
of components and declaring them as Flow types. Sometimes to support flow some
method signatures had to be added. There are some exceptions in which more had
to be done to tame the beast:
- AbstractVideoTrack: put in additional truthy checks for videoTrack.
- Video: add truthy checks for the _videoElement ref.
- shouldRenderVideoTrack function: Some component could pass null for the
  videoTrack argument and Flow wanted that called out explicitly.
- DisplayName: Add a truthy check for the input ref before acting on it.
- NumbersList: Move array checks inline for Flow to comprehend array methods
  could be called. Add type checks in the Object.entries loop as the value is
  assumed to be a mixed type by Flow.
- AbstractToolbarButton: add additional truthy check for passed in type.

react/features/base/react/components/web/MultiSelectAutocomplete.js

@@ -1,7 +1,8 @@
+// @flow
+
 import { MultiSelectStateless } from '@atlaskit/multi-select';
 import AKInlineDialog from '@atlaskit/inline-dialog';
 import _debounce from 'lodash/debounce';
-import PropTypes from 'prop-types';
 import React, { Component } from 'react';
 
 import InlineDialogFailure from './InlineDialogFailure';
@@ -9,118 +10,127 @@ import InlineDialogFailure from './InlineDialogFailure';
 const logger = require('jitsi-meet-logger').getLogger(__filename);
 
 /**
- * A MultiSelect that is also auto-completing.
+ * The type of the React {@code Component} props of
+ * {@link MultiSelectAutocomplete}.
  */
-class MultiSelectAutocomplete extends Component {
+type Props = {
 
     /**
-     * {@code MultiSelectAutocomplete} component's property types.
-     *
-     * @static
+     * The default value of the selected item.
      */
-    static propTypes = {
-        /**
-         * The default value of the selected item.
-         */
-        defaultValue: PropTypes.array,
+    defaultValue: Array<Object>,
 
-        /**
-         * Optional footer to show as a last element in the results.
-         * Should be of type {content: <some content>}
-         */
-        footer: PropTypes.object,
+    /**
+     * Optional footer to show as a last element in the results.
+     * Should be of type {content: <some content>}
+     */
+    footer: Object,
 
-        /**
-         * Indicates if the component is disabled.
-         */
-        isDisabled: PropTypes.bool,
+    /**
+     * Indicates if the component is disabled.
+     */
+    isDisabled: boolean,
 
-        /**
-         * Text to display while a query is executing.
-         */
-        loadingMessage: PropTypes.string,
+    /**
+     * Text to display while a query is executing.
+     */
+    loadingMessage: string,
 
-        /**
-         * The text to show when no matches are found.
-         */
-        noMatchesFound: PropTypes.string,
+    /**
+     * The text to show when no matches are found.
+     */
+    noMatchesFound: string,
 
-        /**
-         * The function called immediately before a selection has been actually
-         * selected. Provides an opportunity to do any formatting.
-         */
-        onItemSelected: PropTypes.func,
+    /**
+     * The function called immediately before a selection has been actually
+     * selected. Provides an opportunity to do any formatting.
+     */
+    onItemSelected: Function,
 
-        /**
-         * The function called when the selection changes.
-         */
-        onSelectionChange: PropTypes.func,
+    /**
+     * The function called when the selection changes.
+     */
+    onSelectionChange: Function,
 
-        /**
-         * The placeholder text of the input component.
-         */
-        placeholder: PropTypes.string,
+    /**
+     * The placeholder text of the input component.
+     */
+    placeholder: string,
 
-        /**
-         * The service providing the search.
-         */
-        resourceClient: PropTypes.shape({
-            makeQuery: PropTypes.func,
-            parseResults: PropTypes.func
-        }).isRequired,
+    /**
+     * The service providing the search.
+     */
+    resourceClient: { makeQuery: Function, parseResults: Function },
 
-        /**
-         * Indicates if the component should fit the container.
-         */
-        shouldFitContainer: PropTypes.bool,
+    /**
+     * Indicates if the component should fit the container.
+     */
+    shouldFitContainer: boolean,
 
-        /**
-         * Indicates if we should focus.
-         */
-        shouldFocus: PropTypes.bool
-    };
+    /**
+     * Indicates if we should focus.
+     */
+    shouldFocus: boolean
+};
 
+/**
+ * The type of the React {@code Component} state of
+ * {@link MultiSelectAutocomplete}.
+ */
+type State = {
+
+    /**
+     * Indicates if the dropdown is open.
+     */
+    isOpen: boolean,
+
+    /**
+     * The text that filters the query result of the search.
+     */
+    filterValue: string,
+
+    /**
+     * Indicates if the component is currently loading results.
+     */
+    loading: boolean,
+
+    /**
+     * Indicates if there was an error.
+     */
+    error: boolean,
+
+    /**
+     * The list of result items.
+     */
+    items: Array<Object>,
+
+    /**
+     * The list of selected items.
+     */
+    selectedItems: Array<Object>
+};
+
+/**
+ * A MultiSelect that is also auto-completing.
+ */
+class MultiSelectAutocomplete extends Component<Props, State> {
     /**
      * Initializes a new {@code MultiSelectAutocomplete} instance.
      *
      * @param {Object} props - The read-only properties with which the new
      * instance is to be initialized.
      */
-    constructor(props) {
+    constructor(props: Props) {
         super(props);
 
         const defaultValue = this.props.defaultValue || [];
 
         this.state = {
-            /**
-             * Indicates if the dropdown is open.
-             */
             isOpen: false,
-
-            /**
-             * The text that filters the query result of the search.
-             */
             filterValue: '',
-
-            /**
-             * Indicates if the component is currently loading results.
-             */
             loading: false,
-
-
-            /**
-             * Indicates if there was an error.
-             */
             error: false,
-
-            /**
-             * The list of result items.
-             */
             items: [],
-
-            /**
-             * The list of selected items.
-             */
             selectedItems: [ ...defaultValue ]
         };
 
@@ -137,7 +147,7 @@ class MultiSelectAutocomplete extends Component {
      * having been selected.
      * @returns {void}
      */
-    setSelectedItems(selectedItems = []) {
+    setSelectedItems(selectedItems: Array<Object> = []) {
         this.setState({ selectedItems });
     }
 
@@ -177,6 +187,8 @@ class MultiSelectAutocomplete extends Component {
         );
     }
 
+    _onFilterChange: (string) => void;
+
     /**
      * Sets the state and sends a query on filter change.
      *
@@ -198,6 +210,8 @@ class MultiSelectAutocomplete extends Component {
         }
     }
 
+    _onRetry: () => void;
+
     /**
      * Retries the query on retry.
      *
@@ -208,6 +222,8 @@ class MultiSelectAutocomplete extends Component {
         this._sendQuery(this.state.filterValue);
     }
 
+    _onSelectionChange: (Object) => void;
+
     /**
      * Updates the selected items when a selection event occurs.
      *
@@ -258,6 +274,8 @@ class MultiSelectAutocomplete extends Component {
         );
     }
 
+    _sendQuery: (string) => void;
+
     /**
      * Sends a query to the resourceClient.
      *