fixed regex in resolve-value.js

This fix will make work, when using nested CSS functions in the same declaration.

See MadLittleMods#96

Author: juliovedovatto

lib/resolve-value.js

@@ -10,7 +10,8 @@ var cloneSpliceParentOntoNodeWhen = require('./clone-splice-parent-onto-node-whe
 // var() = var( <custom-property-name> [, <any-value> ]? )
 // matches `name[, fallback]`, captures "name" and "fallback"
 // See: http://dev.w3.org/csswg/css-variables/#funcdef-var
-var RE_VAR_FUNC = (/var\(\s*(--[^,\s]+?)(?:\s*,\s*(.+))?\s*\)/);
+//var RE_VAR_FUNC = (/var\(\s*(--[^,\s]+?)(?:\s*,\s*(.+))?\s*\)/);
+var RE_VAR_FUNC = (/var\(\s*(--[^,\s]+?)(?:\s*,\s*([^)]+))?\s*\)/);
 
 function toString(value) {
 	return String(value);