[google-maps]: strokeColor is required on Android

## Bug Report

### Plugin(s)
`google-maps@5.3.0`

### Platform(s)
Android

### Current Behavior
When drawing a polyline, the map throws an error on Android with:

```
main.52e9d7a35c851942.js:1 Error: Uncaught (in promise): Error: Unhandled Error: No value for strokeColor.
Error: Unhandled Error: No value for strokeColor.
at returnResult (VM3:770:32)
at win.androidBridge.onmessage (VM3:745:21)
at te (polyfills.57895b56d757dc92.js:1:18910)
at polyfills.57895b56d757dc92.js:1:17986
at polyfills.57895b56d757dc92.js:1:18092
at d (main.52e9d7a35c851942.js:1:1136027)
at te (main.52e9d7a35c851942.js:1:1136237)
at _.invoke (polyfills.57895b56d757dc92.js:1:8747)
at Object.onInvoke (main.52e9d7a35c851942.js:1:906705)
at _.invoke (polyfills.57895b56d757dc92.js:1:8686)
at _.run (polyfills.57895b56d757dc92.js:1:3778)
at polyfills.57895b56d757dc92.js:1:19705
at _.invokeTask (polyfills.57895b56d757dc92.js:1:9432)
at Object.onInvokeTask (main.52e9d7a35c851942.js:1:906521)
at _.invokeTask (polyfills.57895b56d757dc92.js:1:9353)
at _.runTask (polyfills.57895b56d757dc92.js:1:4447)
at U (polyfills.57895b56d757dc92.js:1:11834)
```

### Expected Behavior
Polyline can be drawn without specifying the color or `interface Polyline extends google.maps.PolylineOptions` should have set strokeColor as required and not optional.