Client freezes when selecting text in document viewer on emed.folger.edu

## Bug report form
### Steps to reproduce
1. Trying to annotate on: https://emed.folger.edu/view/1644/AShrew in preparation for a demo in 90 minutes.
2. Page loads. Client loads. But when I select text, the whole thing freezes up. No buttons appear. Can't click to unselect. Nothing.
3. Same behavior in both Chrome and Firefox.

### Expected behaviour
Tell us what should happen.
Selecting text should cause annotate buttons to appear.

### Actual behaviour
Tell us what happens instead.
No buttons appear and whole tab is frozen.

### Browser/system information
Tell us which browser, browser version, and operating system you were using when
you encountered this issue.
Chrome Version 64.0.3282.140
Firefox 58.0.2 (64-bit)

### Additional details

## Feature Request Form
### Problem you are trying to address with this feature

### Your solution

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