Can't process a prop with single letter

[hylin]

Vue.js version

1.0.26

Reproduction Link

https://jsfiddle.net/hylin/jj2sn38p/

Steps to reproduce

1. Use a hyphenated prop with single letter. eg. test-p-r-o-p="demo"
2. There is no way to get the prop in child component

What is Expected?

A way to get hyphenated prop with single letter.

What is actually happening?

When camelize a prop like 'test-p-r-o-p', we get 'testPROP'.
Then hyphenate it, but we get 'test-prop'.
camelize & hyphenate function in lang.js should update to fix this case.