don't test #3480 on IE8

tests/unit/src/unit/issues/Issue3480.hx

@@ -3,7 +3,8 @@ package unit.issues;
 class Issue3480 extends Test {
     function test() {
         #if js
-        eq("{\n\ttoString : 1\n}", Std.string({toString: 1}));
+        if (!js.Browser.supported || js.Browser.navigator.userAgent.indexOf('MSIE 8') == -1) // IE8 doesn't like toString fields at all
+            eq("{\n\ttoString : 1\n}", Std.string({toString: 1}));
         #end
     }
 }