src/vs/editor/browser/viewParts/lines/viewLine.ts/RenderedViewLine/getWidth
class RenderedViewLine:	public getWidth(): number {
		if (!this.domNode) {
			return 0;
		}
		if (this._cachedWidth === -1) {
			this._cachedWidth = this._getReadingTarget(this.domNode).offsetWidth;
		}
		return this._cachedWidth;
	}