Assets/Editor/UpdateTreeColors.js(13,17): BCE0031: Language feature not implemented: UnityEditor.

I have this error Assets/Editor/UpdateTreeColors.js(13,17): BCE0031: Language feature not implemented: UnityEditor.
I am a noob and need help. Here is my code.

@MenuItem("Terrain/Update Tree Lightmap Color")

static function RebuildWithLightmap () {
var tex : Texture2D = Selection.activeObject as Texture2D;
if (tex)
{
if (Terrain.activeTerrain == null || Terrain.activeTerrain.terrainData == null)
{
EditorUtility.DisplayDialog(“No active terrain in the scene”, “No active terrain in the scene”, “Ok”);
return;
}

	Undo.RegisterUndo(Terrain.activeTerrain.terrainData, "Set Tree colors");
	UnityEditor.TerrainLightmapper.UpdateTreeLightmapColor(tex, Terrain.activeTerrain.terrainData);
}
else
	EditorUtility.DisplayDialog("Select a lightmap", "Select a lightmap", "Ok");

}

@MenuItem(“Terrain/Update Tree Color”)
static function RebuildWithColor () {
var tex : Texture2D = Selection.activeObject as Texture2D;
if (tex)
{
if (Terrain.activeTerrain == null || Terrain.activeTerrain.terrainData == null)
{
EditorUtility.DisplayDialog(“No active terrain in the scene”, “No active terrain in the scene”, “Ok”);
return;
}

	Undo.RegisterUndo(Terrain.activeTerrain.terrainData, "Set Tree colors");
	UnityEditor.TerrainLightmapper.UpdateTreeColor(tex, Terrain.activeTerrain.terrainData);
}
else
	EditorUtility.DisplayDialog("Select a lightmap", "Select a lightmap", "Ok");

}

If this is for the island demo, you can just delete the file. It is unneeded.