Update vendor/underscore.

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 + ']';
     };