We need to support negative numbers in calc. e.g: calc(-60% + 70px)

Author: Mohammad Rezaei

src/com/yahoo/platform/yui/compressor/CssCompressor.java

@@ -511,10 +511,10 @@ public void compress(Writer out, int linebreakpos)
         while (m.find()) {
             String s = m.group();
 
-            s = s.replaceAll("(?<=[%|px|em|rem|vw|\\d]+)\\+", " + ");
-            s = s.replaceAll("(?<=[%|px|em|rem|vw|\\d]+)\\-", " - ");
-            s = s.replaceAll("(?<=[%|px|em|rem|vw|\\d]+)\\*", " * ");
-            s = s.replaceAll("(?<=[%|px|em|rem|vw|\\d]+)\\/", " / ");
+            s = s.replaceAll("(?<=[-|%|px|em|rem|vw|\\d]+)\\+", " + ");
+            s = s.replaceAll("(?<=[-|%|px|em|rem|vw|\\d]+)\\-", " - ");
+            s = s.replaceAll("(?<=[-|%|px|em|rem|vw|\\d]+)\\*", " * ");
+            s = s.replaceAll("(?<=[-|%|px|em|rem|vw|\\d]+)\\/", " / ");
 
             m.appendReplacement(sb, s);
         }