Keypress triggering unnecessary layout reflow

[leandrogaspar]

Regardless of need, the IconPicker selectItem() function triggers a layout reflow for each keystroke. This may seems like nitpicking, however, it almost doubles the time spent on Layout. On complex applications/mobile the impact is significant.

selectItem(target, trigger) {
    super.selectItem(target, trigger);
    const item = target || this.defaultItem;
    this.label.innerHTML = item.innerHTML; <-- Layout reflow
  }

Steps for Reproduction

1. Visit https://codepen.io/leandrogaspar/pen/BONZRQ
2. Open Google Chrome Performance tab and start recording
3. Type something on the editor

Expected behavior:
Icon Picker should not trigger layout reflow for each keystroke

Actual behavior:

Platforms:
Chrome Version 68.0.3440.106 (Official Build) (64-bit)

Version:
1.3.6