Calc with + removing space (v. 2.1.7) #330

Are you sure this is not a problem with your configuration? (ask on the
Google Group)

Minify commit/version: 2.1.7
PHP version: PHP/5.6.3

What steps will reproduce the problem?
1. Setup minify style.css
2. Html: Make div 2 inside div 1 (evt overflow hidden).
3. Use for div 2: width: calc(100% + 70px);

Expected output: width:calc(100% + 70px);

Actual output: width:calc(100%+70px);