src/vs/editor/common/core/stringBuilder.ts/StringBuilder/_flushBuffer
class StringBuilder:	private _flushBuffer(): void {
		const bufferString = this._buildBuffer();
		this._bufferLength = 0;

		if (this._completedStrings === null) {
			this._completedStrings = [bufferString];
		} else {
			this._completedStrings[this._completedStrings.length] = bufferString;
		}
	}