Add getArea method where it is necessary.

alaycock · web-flow · commit cc8c76768639 · 2017-01-04T13:56:39.000-07:00
Without this, the `shape.getArea()` call below will cause an error.
diff --git a/README.md b/README.md
@@ -1203,6 +1203,10 @@ class Square extends Shape {
   setLength(length) {
     this.length = length;
   }
+  
+  getArea() {
+    return this.length * this.length;
+  }
 }
 
 function renderLargeShapes(shapes) {

Original file line number	Diff line number	Diff line change
`@@ -1203,6 +1203,10 @@ class Square extends Shape {`
`1203`	`1203`	`setLength(length) {`
`1204`	`1204`	`this.length = length;`
`1205`	`1205`	`}`
	`1206`	`+`
	`1207`	`+getArea() {`
	`1208`	`+return this.length * this.length;`
	`1209`	`+}`
`1206`	`1210`	`}`
`1207`	`1211`
`1208`	`1212`	`function renderLargeShapes(shapes) {`