Update vendor/underscore.

Former-commit-id: 833a6ca3e5a7f9d4a8b22e535d849c106526171e

vendor/underscore/test/objects.js

@@ -52,7 +52,7 @@ $(document).ready(function() {
     result = _.extend({x:'x'}, {a:'a', x:2}, {a:'b'});
     ok(_.isEqual(result, {x:2, a:'b'}), 'extending from multiple source objects last property trumps');
     result = _.extend({}, {a: void 0, b: null});
-    equal(_.keys(result).join(''), 'ab', 'extend does not copy undefined values');
+    equal(_.keys(result).join(''), 'ab', 'extend copies undefined values');
 
     try {
       result = {};

vendor/underscore/underscore.js

@@ -82,10 +82,9 @@
         if (iterator.call(context, obj[i], i, obj) === breaker) return;
       }
     } else {
-      for (var key in obj) {
-        if (_.has(obj, key)) {
-          if (iterator.call(context, obj[key], key, obj) === breaker) return;
-        }
+      var keys = _.keys(obj);
+      for (var i = 0, length = keys.length; i < length; i++) {
+        if (iterator.call(context, obj[keys[i]], keys[i], obj) === breaker) return;
       }
     }
   };
@@ -307,9 +306,9 @@
     var iterator = lookupIterator(value);
     return _.pluck(_.map(obj, function(value, index, list) {
       return {
-        value : value,
-        index : index,
-        criteria : iterator.call(context, value, index, list)
+        value: value,
+        index: index,
+        criteria: iterator.call(context, value, index, list)
       };
     }).sort(function(left, right) {
       var a = left.criteria;
@@ -318,46 +317,41 @@
         if (a > b || a === void 0) return 1;
         if (a < b || b === void 0) return -1;
       }
-      return left.index < right.index ? -1 : 1;
+      return left.index - right.index;
     }), 'value');
   };
 
   // An internal function used for aggregate "group by" operations.
-  var group = function(obj, value, context, behavior) {
-    var result = {};
-    var iterator = lookupIterator(value == null ? _.identity : value);
-    each(obj, function(value, index) {
-      var key = iterator.call(context, value, index, obj);
-      behavior(result, key, value);
-    });
-    return result;
+  var group = function(behavior) {
+    return function(obj, value, context) {
+      var result = {};
+      var iterator = value == null ? _.identity : lookupIterator(value);
+      each(obj, function(value, index) {
+        var key = iterator.call(context, value, index, obj);
+        behavior(result, key, value);
+      });
+      return result;
+    };
   };
 
   // Groups the object's values by a criterion. Pass either a string attribute
   // to group by, or a function that returns the criterion.
-  _.groupBy = function(obj, value, context) {
-    return group(obj, value, context, function(result, key, value) {
-      (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
-    });
-  };
+  _.groupBy = group(function(result, key, value) {
+    (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
+  });
 
-  // Indexes the object's values by a criterion, similar to `groupBy`, but for 
+  // Indexes the object's values by a criterion, similar to `groupBy`, but for
   // when you know that your index values will be unique.
-  _.indexBy = function(obj, value, context) {
-    return group(obj, value, context, function(result, key, value) {
-      result[key] = value;
-    });
-  };
+  _.indexBy = group(function(result, key, value) {
+    result[key] = value;
+  });
 
   // Counts instances of an object that group by a certain criterion. Pass
   // either a string attribute to count by, or a function that returns the
   // criterion.
-  _.countBy = function(obj, value, context) {
-    return group(obj, value, context, function(result, key) {
-      if (!_.has(result, key)) result[key] = 0;
-      result[key]++;
-    });
-  };
+  _.countBy = group(function(result, key, value) {
+    _.has(result, key) ? result[key]++ : result[key] = 1;
+  });
 
   // Use a comparator function to figure out the smallest index at which
   // an object should be inserted so as to maintain order. Uses binary search.
@@ -394,7 +388,7 @@
   // allows it to work with `_.map`.
   _.first = _.head = _.take = function(array, n, guard) {
     if (array == null) return void 0;
-    return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
+    return (n == null) || guard ? array[0] : slice.call(array, 0, n);
   };
 
   // Returns everything but the last entry of the array. Especially useful on
@@ -409,10 +403,10 @@
   // values in the array. The **guard** check allows it to work with `_.map`.
   _.last = function(array, n, guard) {
     if (array == null) return void 0;
-    if ((n != null) && !guard) {
-      return slice.call(array, Math.max(array.length - n, 0));
-    } else {
+    if ((n == null) || guard) {
       return array[array.length - 1];
+    } else {
+      return slice.call(array, Math.max(array.length - n, 0));
     }
   };
 
@@ -444,7 +438,7 @@
     return output;
   };
 
-  // Return a completely flattened version of an array.
+  // Flatten out an array, either recursively (by default), or just one level.
   _.flatten = function(array, shallow) {
     return flatten(array, shallow, []);
   };