Cannot reset "visibility" property on webview view in package.json

[RMacfarlane]

Testing #105764

1. Use the webview view extension sample: https://github.com/Microsoft/vscode-extension-samples/tree/master/webview-view-sample
2. Modify the view contribution point to set "visibility" to "visible"

		"views": {
			"explorer": [
				{
					"type": "webview",
					"id": "calicoColors.colorsView",
					"name": "Calico Colors",
					"visibility": "visible"
				}
			]
		},

3. Run extension and expand the explorer, view is visible as expected
4. Change "visibility" to another value, or remove the property, and rerun the extension

The view seems to now be cached in an expanded state and the new "visibility" value is ignored

[RMacfarlane]

Actually, I think this is working as expected - I think I collapsed and reopened the view, which would prevent the initial state from being picked up again.