Invalid completion items when using dots in completion item label

monaco-editor version: 0.20.0
Browser: Chrome
OS: Windows
Playground code that reproduces the issue:

function getSuggestions(range) {
    return [
        {
            label: 'parameters.In1',
            kind: monaco.languages.CompletionItemKind.Field,
            insertText: 'parameters.In1',
            insertTextRules: null,
            range: range
        }
    ];
}


monaco.languages.registerCompletionItemProvider('javascript', {
    provideCompletionItems: function(model, position) {
        return {
            suggestions: getSuggestions(null)
        };
    }
});

monaco.editor.create(document.getElementById("container"), {
    language: "javascript"
});

I was only able to reproduce this when registering a completion item provider which return completion items with dots in the label/insertText.

Repro steps:

1. Execute the code above
2. Type param and choose the option parameters.In1
3. Type again type
   Result: The completion menu shows an option "parameters" which was not returned by my provider neither exists in the Javascript language.

See the gif below:

Start with the playground reproduction and the registerCompletionItemProvider/provideCompletionItems entry points shown in the issue. Trace how a completion with a dotted label and insertText is processed after selection, then verify that typing again does not create an unregistered parameters item. No repository file or test is named in the report.