Clean column collapsible (#3931)

* Remove unused column_collapsable.js
* Remove old styles
* Extract `> div`  style to independent class

app/javascript/mastodon/components/column_collapsable.js

-import React from 'react';
-import PropTypes from 'prop-types';
-
-export default class ColumnCollapsable extends React.PureComponent {
-
-  static propTypes = {
-    icon: PropTypes.string.isRequired,
-    title: PropTypes.string,
-    fullHeight: PropTypes.number.isRequired,
-    children: PropTypes.node,
-    onCollapse: PropTypes.func,
-  };
-
-  state = {
-    collapsed: true,
-    animating: false,
-  };
-
-  handleToggleCollapsed = () => {
-    const currentState = this.state.collapsed;
-
-    this.setState({ collapsed: !currentState, animating: true });
-
-    if (!currentState && this.props.onCollapse) {
-      this.props.onCollapse();
-    }
-  }
-
-  handleTransitionEnd = () => {
-    this.setState({ animating: false });
-  }
-
-  render () {
-    const { icon, title, fullHeight, children } = this.props;
-    const { collapsed, animating } = this.state;
-
-    return (
-      <div className={`column-collapsable ${collapsed ? 'collapsed' : ''}`} onTransitionEnd={this.handleTransitionEnd}>
-        <div role='button' tabIndex='0' title={`${title}`} className='column-collapsable__button column-icon' onClick={this.handleToggleCollapsed}>
-          <i className={`fa fa-${icon}`} />
-        </div>
-
-        <div className='column-collapsable__content' style={{ height: `${fullHeight}px` }}>
-          {(!collapsed || animating) && children}
-        </div>
-      </div>
-    );
-  }
-
-}

app/javascript/mastodon/components/column_header.js

@@ -132,7 +132,7 @@ export default class ColumnHeader extends React.PureComponent {
         </div>
 
         <div className={collapsibleClassName} onTransitionEnd={this.handleTransitionEnd}>
-          <div>
+          <div className='column-header__collapsible-inner'>
             {(!collapsed || animating) && collapsedContent}
           </div>
         </div>

app/javascript/styles/components.scss

@@ -58,37 +58,6 @@
   position: relative;
 }
 
-.column-collapsable {
-  position: relative;
-
-  .column-collapsable__content {
-    overflow: auto;
-    transition: 300ms ease;
-    opacity: 1;
-    max-height: 70vh;
-  }
-
-  &.collapsed .column-collapsable__content {
-    height: 0 !important;
-    opacity: 0;
-  }
-
-  .column-collapsable__button {
-    color: $primary-text-color;
-    background: lighten($ui-base-color, 8%);
-
-    &:hover {
-      color: $primary-text-color;
-      background: lighten($ui-base-color, 8%);
-    }
-  }
-
-  &.collapsed .column-collapsable__button {
-    color: $ui-primary-color;
-    background: lighten($ui-base-color, 4%);
-  }
-}
-
 .column-icon {
   background: lighten($ui-base-color, 4%);
   color: $ui-primary-color;
@@ -2110,11 +2079,6 @@ button.icon-button.active i.fa-retweet {
   transition: max-height 150ms ease-in-out, opacity 300ms linear;
   opacity: 1;
 
-  & > div {
-    background: lighten($ui-base-color, 8%);
-    padding: 15px;
-  }
-
   &.collapsed {
     max-height: 0;
     opacity: 0.5;
@@ -2125,6 +2089,11 @@ button.icon-button.active i.fa-retweet {
   }
 }
 
+.column-header__collapsible-inner {
+  background: lighten($ui-base-color, 8%);
+  padding: 15px;
+}
+
 .column-header__setting-btn {
   &:hover {
     color: lighten($ui-primary-color, 4%);