Creating a shape from a randomly drawn line

programming flash
1

I have a line randomly being drawn and moved across the stage. Here is the code:

import flash.display.Sprite;

var xValue:Number = 0;  
var yValue:Number = 150;   

//sprite in which the line will be created
var edgeHolder:Sprite = new Sprite();
addChild(edgeHolder);

//define lineStyle and starting positon
edgeHolder.graphics.lineStyle(3,0x00bb00);
edgeHolder.graphics.moveTo(xValue,yValue);  

edgeHolder.addEventListener(Event.ENTER_FRAME, drawRandom);  

function drawRandom(event:Event):void {  
    //reassign the x and y positions
	xValue+=10;  
	yValue = 100 + (Math.random()*150);  
	
    // draw the line to the next point  
    edgeHolder.graphics.lineTo(xValue,yValue); 
	
	 
	
	//move edgeHolder to the left once the line is across the entire stage
	if(xValue>=stage.stageWidth) {
		edgeHolder.x-=10;
	}
}

Is there any simple way to create a filled in shape that covers the entire area of the stage above the line being created? Or any other way of filling in this space?

Thanks.