fix tests

test/compress/arrow.js

@@ -483,6 +483,7 @@ issue_485_crashing_1530: {
         ecma: 6,
         evaluate: true,
         inline: true,
+        side_effects: true,
     }
     input: {
         (function(a) {
@@ -490,9 +491,7 @@ issue_485_crashing_1530: {
             var b = 42;
         })(this);
     }
-    expect: {
-        this, void 0;
-    }
+    expect: {}
 }
 
 issue_2084: {