Improve ESLint rules for JSX (#3608)

* Add react/no-string-refs ESLint rule

* Add react/jsx-boolean-value ESLint rule

* Add react/jsx-closing-bracket-location ESLint rule

* Add react/jsx-indent ESLint rule

* Add react/jsx-curly-spacing ESLint rule

* Add react/jsx-equals-spacing ESLint rule

* Add react/jsx-first-prop-new-line ESLint rule

* Add react/jsx-no-duplicate-props ESLint rule

* Add react/jsx-tag-spacing ESLint rule

app/javascript/mastodon/components/icon_button.js

@@ -76,7 +76,8 @@ class IconButton extends React.PureComponent {
             title={this.props.title}
             className={classes.join(' ')}
             onClick={this.handleClick}
-            style={style}>
+            style={style}
+          >
             <i style={{ transform: `rotate(${rotate}deg)` }} className={`fa fa-fw fa-${this.props.icon}`} aria-hidden='true' />
           </button>
         }