Fix parsing setters/getters (allow keywords for name).

The "key" property was always "set" or "get", which didn't make much sense.
Now it'll be the actual name of the setter/getter (AST_Node), and the
AST_Accessor object itself, which represents the function, won't store any
name.

Close #319

lib/output.js

@@ -1066,10 +1066,14 @@ function OutputStream(options) {
     });
     DEFPRINT(AST_ObjectSetter, function(self, output){
         output.print("set");
+        output.space();
+        self.key.print(output);
         self.value._do_print(output, true);
     });
     DEFPRINT(AST_ObjectGetter, function(self, output){
         output.print("get");
+        output.space();
+        self.key.print(output);
         self.value._do_print(output, true);
     });
     DEFPRINT(AST_Symbol, function(self, output){