Tabbing away from filterable select can cause value to change when it opens a second time

[mollykreis]

🐛 Bug Report

Tabbing away from the nimble-select while filtering can cause the value of the select to unexpectedly change when the select is opened the next time.

💻 Repro or Code Sample

1. Open a filterable select (such as in storybook)
2. Type some text into the filter so that an option other than the currently selected option becomes highlighted in the dropdown
3. Tab away from the component
4. Notice that the select still shows the original value (expected because no new value was committed during the previous interaction)
5. Tab back to the nimble-select
6. Press 'Enter' to open the select
7. Notice the select's value immediately changes to the highlighted option from step 2

🤔 Expected Behavior

Entering text in the select's filter and then closing the select should not leave the component in a state that causes the value to change the next time the select opens.

😯 Current Behavior

The select gets in a state where the value changes immediately when it becomes open again.

💁 Possible Solution

🔦 Context

🌍 Your Environment

• OS & Device: [e.g. MacOS, iOS, Windows, Linux] on [iPhone 7, PC]
• Browser [e.g. Microsoft Edge, Google Chrome, Apple Safari, Mozilla FireFox]
• Version [e.g. 1.8.0]