Text Field touch event does not contain clientX or clientY

[moog16]

related material-components/material-components-web-react#275

The touchstart event listener in text field's foundation.js is bound to this callback function:

this.setPointerXOffset_ = (evt) => this.setTransformOrigin(evt);

  setTransformOrigin(evt) {
    const targetClientRect = evt.target.getBoundingClientRect();
    const evtCoords = {x: evt.clientX, y: evt.clientY};
    const normalizedX = evtCoords.x - targetClientRect.left;
    this.adapter_.setLineRippleTransformOrigin(normalizedX);
  }

When the event is mousedown, the event has clientX and clientY. When the event is a touchstart, clientX and clientY are missing. clientX and clientY are instead found within evt.touches property.

Reproduce

1. put debugger at beginning of setTransformOrigin method
2. start text field demo
3. enter chrome into mobile mode with dev tools
4. click one of the text field's

Result:
You'll notice that evt.clientX or evt.clientY does not exist.