[IconMenu] Fix React warning

[olee]

Changed IconMenu to conditionally add button iconStyle

Resolves #4857
References #5496

• PR has tests / docs demo, and is linted.
• Commit and PR titles begin with [ComponentName], and are in imperative form: "[Component] Fix leaky abstraction".
• Description explains the issue / use-case resolved, and auto-closes the related issue(s) (http://tr.im/vFqem).

[oliviertassinari]

You are right. Thanks 👍 !

[olee]

When can I expect a release with this fix or is there a way to install latest (master) from npm?
npm i material-ui@next only installs some 0.16.0-rc version.

[oliviertassinari]

@olee We release batches every two / three weeks. If you need it asap on your project. Might be best to have a fork until it's released.

[mbrookes]

@olee try:

"dependencies" : {
  "material-ui": "callemall/material-ui",
}

in your package.json, with optional #commit-ish (sha etc.)

You can also manually npm install from a git URL.