Use _.extend instead of the hand-rolled merge

lib/coffee_script/nodes.js

@@ -25,24 +25,11 @@
     return memo;
   };
   // Merge objects.
-  merge = function merge(src, dest) {
-    var __a, __b, fresh, key, val;
-    fresh = {};
-    __a = src;
-    for (key in __a) {
-      val = __a[key];
-      if (__hasProp.call(__a, key)) {
-        ((fresh[key] = val));
-      }
-    }
-    __b = dest;
-    for (key in __b) {
-      val = __b[key];
-      if (__hasProp.call(__b, key)) {
-        ((fresh[key] = val));
-      }
-    }
-    return fresh;
+  merge = function merge(options, overrides) {
+    return _.tap({}, function(fresh) {
+      _.extend(fresh, options);
+      return _.extend(fresh, overrides);
+    });
   };
   // Delete a key from an object, returning the value.
   del = function del(obj, key) {

src/nodes.coffee

@@ -20,11 +20,10 @@ flatten: (list) ->
   memo
 
 # Merge objects.
-merge: (src, dest) ->
-  fresh: {}
-  (fresh[key]: val) for key, val of src
-  (fresh[key]: val) for key, val of dest
-  fresh
+merge: (options, overrides) ->
+  _.tap {}, (fresh) ->
+    _.extend fresh, options
+    _.extend fresh, overrides
 
 # Delete a key from an object, returning the value.
 del: (obj, key) ->