Fix compilation to ES5

Author: jvanbruegge

src/eventHandlers/mousedown.ts

@@ -18,7 +18,9 @@ export function mousedownHandler(
     opts: SortableOptions
 ): [VNode, undefined] {
     const item: Element = ev.currentTarget as Element;
-    const indexClicked = [...item.parentElement.children].indexOf(item);
+    const indexClicked = Array.prototype.slice
+        .call(item.parentElement.children)
+        .indexOf(item);
 
     const children = node.children
         .map(addData)

src/eventHandlers/mousemove.ts

@@ -12,7 +12,7 @@ export function mousemoveHandler(
         .map(n => n.data.dataset.item)
         .filter(n => !!n)[0];
 
-    const siblings = [...item.parentElement.children];
+    const siblings = Array.prototype.slice.call(item.parentElement.children);
     const index = siblings.indexOf(item);
     const ghost = siblings[siblings.length - 1];
     const itemArea = getArea(ghost);

tsconfig.json

@@ -2,10 +2,14 @@
     "compileOnSave": false,
     "compilerOptions":
     {
-        "module": "CommonJS",
+        "moduleResolution": "node",
         "sourceMap": true,
-        "target": "ES6",
-        "outDir": "build"
+        "target": "ES5",
+        "outDir": "build",
+        "lib": [
+            "ES6",
+            "DOM"
+        ]
     },
     "include": [
         "src/**/*.ts",