[object Generator]

25.3 Generator Objects
http://www.ecma-international.org/ecma-262/6.0/#sec-generator-objects
```
C:\Users> node
> GF = function* (){}
[Function: GF]
> GF.constructor.name
'GeneratorFunction'
> G = GF()
{}
> G + ''
'[object Generator]'
```

src/lib/es2015.generator.d.ts

@@ -1,4 +1,13 @@
-interface GeneratorFunction extends Function { }
+interface Generator extends Iterator<any> { }
+
+interface GeneratorFunction {
+    /**
+     * Creates a new Generator object.
+     * @param args A list of arguments the function accepts.
+     */
+    new (...args: any[]): Generator;
+    (...args: any[]): Generator;
+}
 
 interface GeneratorFunctionConstructor {
     /**

src/lib/es2015.symbol.wellknown.d.ts

@@ -137,7 +137,7 @@ interface Function {
     [Symbol.hasInstance](value: any): boolean;
 }
 
-interface GeneratorFunction extends Function {
+interface GeneratorFunction {
     readonly [Symbol.toStringTag]: "GeneratorFunction";
 }