Implement the first and last helpers.

js/test_cases/helpers_last/input1.json

@@ -0,0 +1,23 @@
+{
+  "people": [
+    {
+      "name": "Alice",
+      "pet": "cat"
+    },
+    {
+      "name": "Bob",
+      "pet": "dog"
+    },
+    {
+      "name": "Chris",
+      "pet": "lizard"
+    }
+  ],
+  "toys": [
+    "ball",
+    "bone"
+  ],
+  "scalar": 7,
+  "name": "global name",
+  "pet": "global pet"
+}

js/test_cases/helpers_last/main.dust

@@ -0,0 +1,29 @@
+Tags inside a last{~n}
+=================={~n}
+{#people}
+    {name}{@last petname="fluffy"},{pet}{petname}{/last}
+{/people}{~n}
+
+last inside a scalar{~n}
+===================={~n}
+{#scalar}
+    {name}{@last petname="fluffy"},{pet}{petname}{/last}
+{/scalar}{~n}
+
+Nested last inside another non-array section{~n}
+============================================{~n}
+{#people}
+    {#toys}
+        {name}'s pet {pet} plays with a {.}{@last}, {/last}
+    {/toys}
+{/people}{~n}
+
+Else block inside a last{~n}
+========================{~n}
+{#people}
+    {name}{@last},{pet}{petname}{:else}elseblock{/last}
+{/people}{~n}
+
+Sep outside any section{~n}
+======================={~n}
+{@last}last is printed outside any section{/last}