Fix IfNode when using Array of arbitrary types (which made the cast to [AnyObject] fail)

Stencil/Node.swift

@@ -230,7 +230,7 @@ public class IfNode : NodeType {
     let result = try variable.resolve(context)
     var truthy = false
 
-    if let result = result as? [AnyObject] {
+    if let result = result as? NSArray {
       if result.count > 0 {
         truthy = true
       }

StencilSpecs/Nodes/IfNodeSpec.swift

@@ -82,5 +82,19 @@ describe("IfNode") {
       let node = IfNode(variable: "unknown", trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
       try expect(try node.render(context)) == "false"
     }
+
+    $0.it("renders the truth when array expression is not empty") {
+      let items: Array<[String:AnyObject]> = [["key":"key1","value":42],["key":"key2","value":1337]]
+      let arrayContext = Context(dictionary: ["items": [items]])
+      let node = IfNode(variable: "items", trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
+      try expect(try node.render(arrayContext)) == "true"
+    }
+
+    $0.it("renders the false when array expression is empty") {
+      let emptyItems = Array<[String:AnyObject]>()
+      let arrayContext = Context(dictionary: ["items": emptyItems])
+      let node = IfNode(variable: "items", trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
+      try expect(try node.render(arrayContext)) == "false"
+    }
   }
 }