Nested translation keys with number at the beginning are not found

[macieklamberski]

vue & vue-i18n version

"vue": "^2.0.1",
"vue-i18n": "^4.7.1",

Reproduction Link

http://jsfiddle.net/f9khsu2q/6/

Steps to reproduce

Just run the code and see the output.

What is Expected?

All translation strings should be displayed in the output.

What is actually happening?

In case of translation strings located in root level, all keys are supported (string, mixed, numeric). In case of nested keys, keys that starts with numeric character are not found and full translation keys is displayed instead.