src/vs/editor/browser/viewParts/minimap/minimap.ts/RenderData/_get
class RenderData:	_get(): { imageData: ImageData; rendLineNumberStart: number; lines: MinimapLine[] } {
		const tmp = this._renderedLines._get();
		return {
			imageData: this._imageData,
			rendLineNumberStart: tmp.rendLineNumberStart,
			lines: tmp.lines
		};
	}