Bug Report

• Package version(s): 5.64.1
• Browser and OS versions: PhantomJS

Priorities and help requested (not applicable if asking question):

Are you willing to submit a PR to fix? Yes. The culprit is BaseButton.tsx method _onRenderDescription the description is pulled off this.props instead of the passed in props object.

Requested priority: High

Products/sites affected: Yammer

Describe the issue:

Oddly when we try to pull our UI library that uses a new Fabric version into our front end codebase, our jasmine unit tests blow on with the following error:

    >> :9747 logCapturedError
    >> TypeError: undefined is not an object (evaluating 'this.props') at
    >> undefined:186 _onRenderDescription
    >> :161 _onRenderTextContents
    >> :0
    >> :133 _onRenderContent
    >> :110 render

...a bunch of stack trace

   >> The above error occurred in the <BaseButton> component:
    >>     in BaseButton (created by Button)
    >>     in Button
    >>     in Provider

Expected behavior:

Not to blow up when we import the new version.