Fix typo in simple-polygon.js LayoutTest helper

LayoutTests/fast/shapes/resources/simple-polygon.js

 // The functions in this file are intended to be used to test non-complex polygons
 // where horizontal lines that overlap the polygon only cross the polygon twice.
 function createPolygon(vertices) {
     var xCoordinates = vertices.map( function(p) { return p.x; } );
     var yCoordinates = vertices.map( function(p) { return p.y; } );
     return {
         vertices: vertices,
         minX: Math.min.apply(null, xCoordinates),
         maxX: Math.max.apply(null, xCoordinates),
         minY: Math.min.apply(null, yCoordinates),
@@ skipping 88 matching lines @@
         return i1;
 
     return [Math.max(i1[0], i2[0]), Math.min(i1[1], i2[1])];
 }
 
 // Generate an "X X ..." string that contains enough characters to fill the polygon. Each
 // character occupies a lineHeight size square cell, the top of first line of characters is aligned
 // with the the polygon's bounds minimum Y value, and each line of characters fills the interior
 // of the polygon.
 
-function generatePolygonContentString(polygon, lineheight) {
+function generatePolygonContentString(polygon, lineHeight) {
     var result = "";
 
     for (var y = polygon.minY; y < polygon.maxY; y += lineHeight) {
         var xIntercepts = polygonLineIntercepts(polygon, y, lineHeight);
         var lengthInCells = Math.floor(xIntercepts[1] / lineHeight) - Math.ceil(xIntercepts[0] / lineHeight);
         for (var i = 0; i < lengthInCells / 2; i++)
             result += "X ";  // all lines end in a space, to enable line breaking
     }
 
     return result;
@@ skipping 118 matching lines @@
     positionInformativeText("informative-text", stylesheet, polygon, lineHeight)
 }
 
 function createPolygonShapeInsideTestCaseExpected() {
     var stylesheet = document.getElementById("stylesheet").sheet;
     var polygon = createPolygon(vertices);
     generateSimulatedPolygonShapeInsideElement("polygon-shape-inside", stylesheet, polygon, lineHeight);
     generatePolygonSVGElements("polygon-svg-shape", stylesheet, polygon, lineHeight);
     positionInformativeText("informative-text", stylesheet, polygon, lineHeight)
 }