Minor fixes.

Fixed a bug that could appear with compression enabled,
and minor tabbing issues in tests.

lib/less/tree/ruleset.js

@@ -198,7 +198,7 @@ tree.Ruleset.prototype = {
         }
         css.push(rulesets);
 
-        return css.join('');
+        return css.join('')  + (env.compress ? '\n' : '');
     },
 
     joinSelectors: function (paths, context, selectors) {

test/less/debug/import/test.less

@@ -1,21 +1,21 @@
 .mixin_import1() {
-	@media all {
-	    .tst {
-		    color: black;
-	        @media screen {
-				color: red;
-			    .tst3 {
-					color: white;
-			    }
-		    }
-	    }
-	}
+    @media all {
+        .tst {
+            color: black;
+            @media screen {
+                color: red;
+                .tst3 {
+                    color: white;
+                }
+            }
+        }
+    }
 }
 
 .mixin_import2() {
     .tst2 {
-	    color: white;
-	}
+        color: white;
+    }
 }
 
 .tst3 {