New Rule: Do not allow generation of new objects in props

[benbayard]

Similar to jsx-no-lambda, if in a prop you do:

<MyComponent 
  style={{display: 'block'}}
/>

this will force any pure component to re-render every time.

Ideally, we could check in render to see if any new objects are generated there. Such as:

render() {
  const style = {display: 'block'};

  return <MyComponent 
    style={style}
  />
}

but that could be a separate rule.

[IllusionMH]

Had similar thought during jsx-no-lambda rewrite.

More ideal case described above - move style variable outside of component. 😃

Also I'd like to suggest further improvements for both rule proposed in this issue as well as for jsx-no-lambda:

• For this rule - also track array literals passed directly to attributes.
• For both - track for default (or fallback) values directly in jsx attributes (e.g. <List items={props.items || []} />)

See React.js pure render performance anti-pattern for the reference.

[benbayard]

Another thing to consider would be:

<MyComponent myProp={condition ? realValue : {}} />

[adidahiya]

Closing due to deprecation timeline, see #210