[misc] Specify length of toArray return type (#5766)

Author: mongoose700

ts3.1-typing-tests/moment-tests.ts

@@ -161,6 +161,8 @@ var getMonth: number = moment().month();
 var getQuater: number = moment().quarter();
 var getYear: number = moment().year();
 
+var date: [number, number, number, number, number, number, number] = moment().toArray();
+
 moment().hours(0).minutes(0).seconds(0).milliseconds(0);
 
 var a3 = moment([2011, 0, 1, 8]);

ts3.1-typings/moment.d.ts

@@ -573,7 +573,7 @@ declare namespace moment {
 
     diff(b: MomentInput, unitOfTime?: unitOfTime.Diff, precise?: boolean): number;
 
-    toArray(): number[];
+    toArray(): [number, number, number, number, number, number, number];
     toDate(): Date;
     toISOString(keepOffset?: boolean): string;
     inspect(): string;