PDF Embed API issue with Chinese characters

This issue is easy to be replicate via Github demo(https://github.com/adobe/pdf-embed-api-samples😞

1. Edit the demo to open a PDF with editable text box, and allow multiline input

2. Try input below Chinese characters:

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dfadsf
顶顶顶顶顶顶顶顶顶顶顶顶
顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶
水水水水水水水水水水水水水水水水水水
sssssssssssssssssss呃呃呃呃呃呃呃呃呃呃呃呃呃ddd 
顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶顶
反反复复烦烦烦烦烦烦烦烦烦烦烦烦烦烦烦

====

3. Click other area in browser to lose focus

4. Garbled characters displayed: