Tries to trigger setters of string expressions, resulting in `Left side of assignment is not a reference` or `Invalid setter function body`

[cheapsteak]

fiddle: http://jsfiddle.net/xjbnttw7/1/

in Chrome: this warning is given Invalid setter function body: 'bar'

in Safari and IE, we get ReferenceError: Left side of assignment is not a reference.

This causes IE10 apps to break, but other browsers seem to be fine ignoring it

[cheapsteak]

I wonder if this is the same issue as https://github.com/yyx990803/vue/issues/776

edit: yup, same bug (namniak is on my team). Feel free to close and move this over.

[yyx990803]

Fixed now on dev branch.