fix: support arrow function name

Author: axetroy

src/evaluate.ts

@@ -781,8 +781,10 @@ const evaluate_map: EvaluateMap = {
       }
     };
 
-    // TODO: define function name
-    Object.defineProperty(func, "length", {value: node.params.length});
+    Object.defineProperties(func,{
+      length:{value:node.params.length},
+      name: {value:node.id ? node.id.name : ""}
+    })
 
     return func;
   },

test/ArrowFunctionExpression.test.ts

@@ -36,6 +36,7 @@ module.exports = func;
 
   t.true(typeof func === "function");
   t.deepEqual(func.length, 0);
+  t.deepEqual(func.name, "");
   t.deepEqual(func(), "hello undefined");
 });