diff --git a/vendor/underscore/test/functions.js b/vendor/underscore/test/functions.js
index 8d2b4dbb3..f696bd648 100644
--- a/vendor/underscore/test/functions.js
+++ b/vendor/underscore/test/functions.js
@@ -475,9 +475,9 @@
   });
 
   QUnit.test('debounce asap', function(assert) {
-    assert.expect(4);
+    assert.expect(6);
     var done = assert.async();
-    var a, b;
+    var a, b, c;
     var counter = 0;
     var incr = function(){ return ++counter; };
     var debouncedIncr = _.debounce(incr, 64, true);
@@ -489,7 +489,13 @@
     _.delay(debouncedIncr, 16);
     _.delay(debouncedIncr, 32);
     _.delay(debouncedIncr, 48);
-    _.delay(function(){ assert.equal(counter, 1, 'incr was debounced'); done(); }, 128);
+    _.delay(function(){
+      assert.equal(counter, 1, 'incr was debounced');
+      c = debouncedIncr();
+      assert.equal(c, 2);
+      assert.equal(counter, 2, 'incr was called again');
+      done();
+    }, 128);
   });
 
   QUnit.test('debounce asap cancel', function(assert) {
diff --git a/vendor/underscore/test/objects.js b/vendor/underscore/test/objects.js
index 614d1cd8f..fa1d9e3e3 100644
--- a/vendor/underscore/test/objects.js
+++ b/vendor/underscore/test/objects.js
@@ -565,6 +565,14 @@
     assert.equal(_.isEqual({a: 0}, {a: -0}), false);
     assert.equal(_.isEqual([NaN], [NaN]), true);
     assert.equal(_.isEqual({a: NaN}, {a: NaN}), true);
+
+    if (typeof Symbol !== 'undefined') {
+      var symbol = Symbol('x');
+      assert.strictEqual(_.isEqual(symbol, symbol), true, 'A symbol is equal to itself');
+      assert.strictEqual(_.isEqual(symbol, Object(symbol)), true, 'Even when wrapped in Object()');
+      assert.strictEqual(_.isEqual(symbol, null), false, 'Different types are not equal');
+    }
+
   });
 
   QUnit.test('isEmpty', function(assert) {
@@ -673,6 +681,100 @@
     assert.ok(_.isBoolean(false), 'and so is false');
   });
 
+  QUnit.test('isMap', function(assert) {
+    assert.ok(!_.isMap('string'), 'a string is not a map');
+    assert.ok(!_.isMap(2), 'a number is not a map');
+    assert.ok(!_.isMap({}), 'an object is not a map');
+    assert.ok(!_.isMap(false), 'a boolean is not a map');
+    assert.ok(!_.isMap(void 0), 'undefined is not a map');
+    assert.ok(!_.isMap([1, 2, 3]), 'an array is not a map');
+    if (typeof Set === 'function') {
+      assert.ok(!_.isMap(new Set()), 'a set is not a map');
+    }
+    if (typeof WeakSet === 'function') {
+      assert.ok(!_.isMap(new WeakSet()), 'a weakset is not a map');
+    }
+    if (typeof WeakMap === 'function') {
+      assert.ok(!_.isMap(new WeakMap()), 'a weakmap is not a map');
+    }
+    if (typeof Map === 'function') {
+      var keyString = 'a string';
+      var obj = new Map();
+      obj.set(keyString, 'value');
+      assert.ok(_.isMap(obj), 'but a map is');
+    }
+  });
+
+  QUnit.test('isWeakMap', function(assert) {
+    assert.ok(!_.isWeakMap('string'), 'a string is not a weakmap');
+    assert.ok(!_.isWeakMap(2), 'a number is not a weakmap');
+    assert.ok(!_.isWeakMap({}), 'an object is not a weakmap');
+    assert.ok(!_.isWeakMap(false), 'a boolean is not a weakmap');
+    assert.ok(!_.isWeakMap(void 0), 'undefined is not a weakmap');
+    assert.ok(!_.isWeakMap([1, 2, 3]), 'an array is not a weakmap');
+    if (typeof Set === 'function') {
+      assert.ok(!_.isWeakMap(new Set()), 'a set is not a weakmap');
+    }
+    if (typeof WeakSet === 'function') {
+      assert.ok(!_.isWeakMap(new WeakSet()), 'a weakset is not a weakmap');
+    }
+    if (typeof Map === 'function') {
+      assert.ok(!_.isWeakMap(new Map()), 'a map is not a weakmap');
+    }
+    if (typeof WeakMap === 'function') {
+      var keyObj = {}, obj = new WeakMap();
+      obj.set(keyObj, 'value');
+      assert.ok(_.isWeakMap(obj), 'but a weakmap is');
+    }
+  });
+
+  QUnit.test('isSet', function(assert) {
+    assert.ok(!_.isSet('string'), 'a string is not a set');
+    assert.ok(!_.isSet(2), 'a number is not a set');
+    assert.ok(!_.isSet({}), 'an object is not a set');
+    assert.ok(!_.isSet(false), 'a boolean is not a set');
+    assert.ok(!_.isSet(void 0), 'undefined is not a set');
+    assert.ok(!_.isSet([1, 2, 3]), 'an array is not a set');
+    if (typeof Map === 'function') {
+      assert.ok(!_.isSet(new Map()), 'a map is not a set');
+    }
+    if (typeof WeakMap === 'function') {
+      assert.ok(!_.isSet(new WeakMap()), 'a weakmap is not a set');
+    }
+    if (typeof WeakSet === 'function') {
+      assert.ok(!_.isSet(new WeakSet()), 'a weakset is not a set');
+    }
+    if (typeof Set === 'function') {
+      var obj = new Set();
+      obj.add(1).add('string').add(false).add({});
+      assert.ok(_.isSet(obj), 'but a set is');
+    }
+  });
+
+  QUnit.test('isWeakSet', function(assert) {
+
+    assert.ok(!_.isWeakSet('string'), 'a string is not a weakset');
+    assert.ok(!_.isWeakSet(2), 'a number is not a weakset');
+    assert.ok(!_.isWeakSet({}), 'an object is not a weakset');
+    assert.ok(!_.isWeakSet(false), 'a boolean is not a weakset');
+    assert.ok(!_.isWeakSet(void 0), 'undefined is not a weakset');
+    assert.ok(!_.isWeakSet([1, 2, 3]), 'an array is not a weakset');
+    if (typeof Map === 'function') {
+      assert.ok(!_.isWeakSet(new Map()), 'a map is not a weakset');
+    }
+    if (typeof WeakMap === 'function') {
+      assert.ok(!_.isWeakSet(new WeakMap()), 'a weakmap is not a weakset');
+    }
+    if (typeof Set === 'function') {
+      assert.ok(!_.isWeakSet(new Set()), 'a set is not a weakset');
+    }
+    if (typeof WeakSet === 'function') {
+      var obj = new WeakSet();
+      obj.add({x: 1}, {y: 'string'}).add({y: 'string'}).add({z: [1, 2, 3]});
+      assert.ok(_.isWeakSet(obj), 'but a weakset is');
+    }
+  });
+
   QUnit.test('isFunction', function(assert) {
     assert.ok(!_.isFunction(void 0), 'undefined vars are not functions');
     assert.ok(!_.isFunction([1, 2, 3]), 'arrays are not functions');
diff --git a/vendor/underscore/underscore.js b/vendor/underscore/underscore.js
index 78c709bd3..bddfdc9f1 100644
--- a/vendor/underscore/underscore.js
+++ b/vendor/underscore/underscore.js
@@ -20,6 +20,7 @@
 
   // Save bytes in the minified (but not gzipped) version:
   var ArrayProto = Array.prototype, ObjProto = Object.prototype;
+  var SymbolProto = typeof Symbol !== 'undefined' ? Symbol.prototype : null;
 
   // Create quick reference variables for speed access to core prototypes.
   var push = ArrayProto.push,
@@ -218,12 +219,8 @@
 
   // Return the first value which passes a truth test. Aliased as `detect`.
   _.find = _.detect = function(obj, predicate, context) {
-    var key;
-    if (isArrayLike(obj)) {
-      key = _.findIndex(obj, predicate, context);
-    } else {
-      key = _.findKey(obj, predicate, context);
-    }
+    var keyFinder = isArrayLike(obj) ? _.findIndex : _.findKey;
+    var key = keyFinder(obj, predicate, context);
     if (key !== void 0 && key !== -1) return obj[key];
   };
 
@@ -442,7 +439,7 @@
       // Keep surrogate pair characters together
       return obj.match(reStrSymbol);
     }
-    if (isArrayLike(obj)) return _.map(obj, _.identity);
+    if (isArrayLike(obj)) return _.map(obj);
     return _.values(obj);
   };
 
@@ -494,7 +491,7 @@
 
   // Trim out all falsy values from an array.
   _.compact = function(array) {
-    return _.filter(array, _.identity);
+    return _.filter(array);
   };
 
   // Internal implementation of a recursive `flatten` function.
@@ -859,12 +856,12 @@
     };
 
     var debounced = restArgs(function(args) {
-      var callNow = immediate && !timeout;
       if (timeout) clearTimeout(timeout);
-      if (callNow) {
+      if (immediate) {
+        var callNow = !timeout;
         timeout = setTimeout(later, wait);
-        result = func.apply(this, args);
-      } else if (!immediate) {
+        if (callNow) result = func.apply(this, args);
+      } else {
         timeout = _.delay(later, wait, this, args);
       }
 
@@ -1195,6 +1192,8 @@
         // millisecond representations. Note that invalid dates with millisecond representations
         // of `NaN` are not equivalent.
         return +a === +b;
+      case '[object Symbol]':
+        return SymbolProto.valueOf.call(a) === SymbolProto.valueOf.call(b);
     }
 
     var areArrays = className === '[object Array]';
@@ -1285,8 +1284,8 @@
     return type === 'function' || type === 'object' && !!obj;
   };
 
-  // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError.
-  _.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error', 'Symbol'], function(name) {
+  // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError, isMap, isWeakMap, isSet, isWeakSet.
+  _.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error', 'Symbol', 'Map', 'WeakMap', 'Set', 'WeakSet'], function(name) {
     _['is' + name] = function(obj) {
       return toString.call(obj) === '[object ' + name + ']';
     };