Fix dropdown menu positions when scrolling (#22916)

* Update react-overlays to latest version

* Fix breaking changes in dropdown menus

* Use react-overlays built-in arrow positioning feature
* Re-implemented `.dropdown-menu__arrow` to have a defined width and height to improve positioning
* Moved wrapping div (`.dropdown-menu` from `DropdownMenu` to `Dropdown`)
* Wrap button in a span to solve issue with ref
* Temporarily remove animations

* Fix breaking changes in emoji picker

* Wrap EmojiPickerMenu in a div where react-overlays’ ref is added

* Fix breaking changes in language dropdown

* Fix breaking changes in privacy dropdown

* Fix breaking changes in search form

* Add animations back using `@keyframes`

* Fix arrow color in light theme

* Fix linting issue

* Remove unused `mounted` state

* Remove `placement` state from components and redux

And remove the placement state from props of the menu components.

* Remove abolution position to fix flip issue

* Remove z-index to fix modals and overlay positions

* Fix lint issues

* Set placement in privacy and language components

Copy the placement state into the `PrivacyDropdown` and `LanguageDropdown` components, to apply correct styling to the buttons depending on which placement the Overlay has.

* Move `placement` state to correct component

app/javascript/mastodon/features/compose/components/emoji_picker_dropdown.js

@@ -2,7 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
 import { EmojiPicker as EmojiPickerAsync } from '../../ui/util/async-components';
-import Overlay from 'react-overlays/lib/Overlay';
+import Overlay from 'react-overlays/Overlay';
 import classNames from 'classnames';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import { supportsPassiveEvents } from 'detect-passive-events';
@@ -154,9 +154,6 @@ class EmojiPickerMenu extends React.PureComponent {
     onClose: PropTypes.func.isRequired,
     onPick: PropTypes.func.isRequired,
     style: PropTypes.object,
-    placement: PropTypes.string,
-    arrowOffsetLeft: PropTypes.string,
-    arrowOffsetTop: PropTypes.string,
     intl: PropTypes.object.isRequired,
     skinTone: PropTypes.number.isRequired,
     onSkinTone: PropTypes.func.isRequired,
@@ -324,14 +321,13 @@ class EmojiPickerDropdown extends React.PureComponent {
   state = {
     active: false,
     loading: false,
-    placement: null,
   };
 
   setRef = (c) => {
     this.dropdown = c;
   }
 
-  onShowDropdown = ({ target }) => {
+  onShowDropdown = () => {
     this.setState({ active: true });
 
     if (!EmojiPicker) {
@@ -346,9 +342,6 @@ class EmojiPickerDropdown extends React.PureComponent {
         this.setState({ loading: false, active: false });
       });
     }
-
-    const { top } = target.getBoundingClientRect();
-    this.setState({ placement: top * 2 < innerHeight ? 'bottom' : 'top' });
   }
 
   onHideDropdown = () => {
@@ -382,7 +375,7 @@ class EmojiPickerDropdown extends React.PureComponent {
   render () {
     const { intl, onPickEmoji, onSkinTone, skinTone, frequentlyUsedEmojis, button } = this.props;
     const title = intl.formatMessage(messages.emoji);
-    const { active, loading, placement } = this.state;
+    const { active, loading } = this.state;
 
     return (
       <div className='emoji-picker-dropdown' onKeyDown={this.handleKeyDown}>
@@ -394,16 +387,22 @@ class EmojiPickerDropdown extends React.PureComponent {
           />}
         </div>
 
-        <Overlay show={active} placement={placement} target={this.findTarget}>
-          <EmojiPickerMenu
-            custom_emojis={this.props.custom_emojis}
-            loading={loading}
-            onClose={this.onHideDropdown}
-            onPick={onPickEmoji}
-            onSkinTone={onSkinTone}
-            skinTone={skinTone}
-            frequentlyUsedEmojis={frequentlyUsedEmojis}
-          />
+        <Overlay show={active} placement={'bottom'} target={this.findTarget} popperConfig={{ strategy: 'fixed' }}>
+          {({ props, placement })=> (
+            <div {...props} style={{ ...props.style, width: 299 }}>
+              <div className={`dropdown-animation ${placement}`}>
+                <EmojiPickerMenu
+                  custom_emojis={this.props.custom_emojis}
+                  loading={loading}
+                  onClose={this.onHideDropdown}
+                  onPick={onPickEmoji}
+                  onSkinTone={onSkinTone}
+                  skinTone={skinTone}
+                  frequentlyUsedEmojis={frequentlyUsedEmojis}
+                />
+              </div>
+            </div>
+          )}
         </Overlay>
       </div>
     );