src/vs/editor/common/viewModel/viewModelLines.ts/IdentityCoordinatesConverter/modelPositionIsVisible
class IdentityCoordinatesConverter:	public modelPositionIsVisible(modelPosition: Position): boolean {
		const lineCount = this._lines.model.getLineCount();
		if (modelPosition.lineNumber < 1 || modelPosition.lineNumber > lineCount) {
			// invalid arguments
			return false;
		}
		return true;
	}