fix: use content_ insead of content (#674)

Author: ANDRES SARMIENTO TOBON

lib/css-base.js

@@ -48,10 +48,10 @@ module.exports = function(useSourceMap) {
 };
 
 function cssWithMappingToString(item, useSourceMap) {
-	var content = item[1] || '';
+	var content_ = item[1] || '';
 	var cssMapping = item[3];
 	if (!cssMapping) {
-		return content;
+		return content_;
 	}
 
 	if (useSourceMap && typeof btoa === 'function') {
@@ -60,10 +60,10 @@ function cssWithMappingToString(item, useSourceMap) {
 			return '/*# sourceURL=' + cssMapping.sourceRoot + source + ' */'
 		});
 
-		return [content].concat(sourceURLs).concat([sourceMapping]).join('\n');
+		return [content_].concat(sourceURLs).concat([sourceMapping]).join('\n');
 	}
 
-	return [content].join('\n');
+	return [content_].join('\n');
 }
 
 // Adapted from convert-source-map (MIT)