Maths is required to be in parenthesis in variables.less

according less1.4.0 (currently 1.4.0 Beta)Maths is required to be in parenthesis.

in variables.less 

    @inputHeight:                   @baseLineHeight + 10px;

in previous version of less will compiled to 

    @inputHeight: 30px;

but in version 1.4+ it will compiled to 

    @inputHeight : 20px +10px;

so I modified to 

    @inputHeight:                   (@baseLineHeight + 10px);