Method toggleM3

src/dev-app/dev-app/dev-app-layout.ts:223–236

(value = !this.state.m3Enabled)

  }

  toggleM3(value = !this.state.m3Enabled) {
    // We need to diff this one since it's a bit more expensive to toggle.
    if (value !== this.state.m3Enabled) {
      (document.getElementById('theme-styles') as HTMLLinkElement).href = value
        ? 'theme-m3.css'
        : 'theme.css';
    }

    this._iconRegistry.setDefaultFontSetClass(
      value ? 'material-symbols-outlined' : 'material-icons',
    );
    this.state.m3Enabled = value;
    setAppState(this.state);
  }

  toggleColorApiBackCompat(value = !this.state.colorApiBackCompat) {
    this.state.colorApiBackCompat = value;