src/vs/editor/browser/viewParts/lines/viewLines.ts/ViewLines/_visibleRangesForLineRange
class ViewLines:	private _visibleRangesForLineRange(lineNumber: number, startColumn: number, endColumn: number): VisibleRanges | null {
		if (this.shouldRender()) {
			// Cannot read from the DOM because it is dirty
			// i.e. the model & the dom are out of sync, so I'd be reading something stale
			return null;
		}

		if (lineNumber < this._visibleLines.getStartLineNumber() || lineNumber > this._visibleLines.getEndLineNumber()) {
			return null;
		}

		return this._visibleLines.getVisibleLine(lineNumber).getVisibleRangesForRange(lineNumber, startColumn, endColumn, new DomReadingContext(this.domNode.domNode, this._textRangeRestingSpot));
	}