Mangle class names correctly

lib/scope.js

@@ -66,7 +66,11 @@ SymbolDef.prototype = {
             || (!options.eval && (this.scope.uses_eval || this.scope.uses_with))
             || (options.keep_fnames
                 && (this.orig[0] instanceof AST_SymbolLambda
-                    || this.orig[0] instanceof AST_SymbolDefun));
+                    || this.orig[0] instanceof AST_SymbolDefun))
+            || this.orig[0] instanceof AST_SymbolMethod
+            || (options.keep_classnames
+                && (this.orig[0] instanceof AST_SymbolClass
+                    || this.orig[0] instanceof AST_SymbolDefClass));
     },
     mangle: function(options) {
         var cache = options.cache && options.cache.props;
@@ -379,7 +383,8 @@ AST_Toplevel.DEFMETHOD("_default_mangler_options", function(options){
         sort        : false,
         toplevel    : false,
         screw_ie8   : false,
-        keep_fnames : false
+        keep_fnames : false,
+        keep_classnames : false
     });
 });
 

test/compress/harmony.js

@@ -233,6 +233,24 @@ class_name_can_be_mangled: {
     }
 }
 
+class_name_can_be_preserved: {
+    mangle = {
+        keep_classnames: true
+    }
+    input: {
+        function x() {
+            (class Baz { });
+            class Foo {};
+        }
+    }
+    expect: {
+        function x() {
+            (class Baz { });
+            class Foo {};
+        }
+    }
+}
+
 number_literals: {
     input: {
         0b1001;