Hi! JSX attribute parsing does not produce the expected result to me and is escaped too early (before being handled aas a regular var by react). Attributes like title or value are not properly rendered as a result.

Input Code

var src = "<div title='café'></div>";

var result = require("babel-core").transform(src, { 
  plugins: ["syntax-jsx"]
  // or: plugins: ["transform-react-jsx"]
})

console.log(result.code)

Expected Behavior

<div title="café"></div>;

Current Behavior

<div title="caf\xE9"></div>;

Details

Relevant and stripped down AST produced by babylon:

"openingElement": {
  "type": "JSXOpeningElement",
  "attributes": [
    { "type": "JSXAttribute"
      "name": {
	"type": "JSXIdentifier",
	"name": "title"
      },
      "value": {
	"type": "StringLiteral",
	"extra": null,
	"value": "café"
      }
    }]
}

The value being a StringLiteral with no extra, it is handled in babel-generator (lib/generators/types.js) as a StringLiteral and fully escaped in jsesc (a regular var assignment - eg: var x = 'café' - has a node.extra element : {value: .., rawValue: ...} that prevents it from being escaped inside jsesc).

I'm not sure what the fix is but I think we should treat JSX attributes as regular assignment.
A simple fix would be to remove the "node.extra = null;" in jsxParseAttributeValue (it does work, verified).
But I guess it is here for a reason?

I can make a pull request if you see the proper way to fix it.
Thank you!

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