nRF52 crashes with longer strings in .print()

**Describe the bug**
Passing in strings over a certain length freezes the device.
May be related to buffer overflow? looks like it crashes after 64 characters.

**Set up (please complete the following information)**
- nRF52840 Feather Express
- TinyUSB library version: 0.8.2
- MacOS 10.15.4
- Chrome 83

**To Reproduce**
Steps to reproduce the behavior:
1. Open `webusb_serial` example [here](https://github.com/adafruit/Adafruit_TinyUSB_Arduino/blob/master/examples/WebUSB/webusb_serial/webusb_serial.ino#L79)
2. change line *79* from
`if ( connected ) usb_web.println("TinyUSB WebUSB Serial example");`
to
`if ( connected ) usb_web.println("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.");`
3. Compiles & upload as expected
4. Connect via https://adafruit.github.io/Adafruit_TinyUSB_Arduino/examples/webusb-serial/
5. Notice expected string gets only partially returned and devices is unresponsive.

**Expected behavior**
Full string is printed out via web_usb without crashing

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Additional context**
Seems to work as expected on SAMD21 boards

Tested in Chrome 83.0.4103.14 and Brave browser (Chromium)

Start with examples/WebUSB/webusb_serial/webusb_serial.ino at line 79 and reproduce the long-string case on an nRF52840 Feather Express using the stated browser and TinyUSB versions. Compare the behavior with SAMD21 boards; done means the complete string is returned through WebUSB without the device becoming unresponsive.

Written by the indexing model from the issue text.