bug#30225: 27.0.50; jsx: Arrow function in attribute breaks indentation

[Mitchel Humpherys <mitch.special@gmail.com>]

I've noticed an indentation bug in js-jsx-mode.

The following code doesn't indent properly (note the `value` attribute on the `select`):

class MySelect extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            value: "",
        };
    }

    render() {
        return (
            <select style={{paddingRight: "10px"}}
                    onChange={e => this.setState({value: e.target.value})}
              value={this.state.value}>
              <option>Hi</option>
            </select>
        );
    }
}

However, when I move the `onChange` arrow function out it indents fine:

class MySelect extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            value: "",
        };
        this.onChange = this.onChange.bind(this);
    }

    render() {
        return (
            <select style={{paddingRight: "10px"}}
                    onChange={this.onChange}
                    value={this.state.value}>
              <option>Hi</option>
            </select>
        );
    }

    onChange(e) {
        this.setState({value: e.target.value});
    }
}




In GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
 of 2018-01-22 built on grinchel
Repository revision: 2df391c202eeee0d575980555443a5e81b8f6b1f
Windowing system distributor 'Fedora Project', version 11.0.11906000
System Description: Fedora release 27 (Twenty Seven)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set [2 times]
Indenting region...done
user-error: Beginning of history; no preceding item
Making completion list...
user-error: Beginning of history; no preceding item

Configured using:
 'configure --prefix=/home/mgalgs/opt/emacs-git'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LCMS2

Important settings:
  value of $LC_CTYPE: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: JSX

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config
gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils js advice sgml-mode dom json
map seq byte-opt gv bytecomp byte-compile cconv imenu thingatpt cc-mode
cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs cl-loaddefs cl-lib elec-pair time-date mule-util tooltip
eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 121749 8471)
 (symbols 48 23352 1)
 (miscs 40 54 97)
 (strings 32 37829 1944)
 (string-bytes 1 1118347)
 (vectors 16 17941)
 (vector-slots 8 534418 8920)
 (floats 8 52 297)
 (intervals 56 243 0)
 (buffers 992 13))