Bump to v4.7.0.

toNumber.js

@@ -1,5 +1,6 @@
 import isFunction from './isFunction';
 import isObject from './isObject';
+import isSymbol from './isSymbol';
 
 /** Used as references for various `Number` constants. */
 var NAN = 0 / 0;
@@ -24,6 +25,7 @@ var freeParseInt = parseInt;
  *
  * @static
  * @memberOf _
+ * @since 4.0.0
  * @category Lang
  * @param {*} value The value to process.
  * @returns {number} Returns the number.
@@ -42,12 +44,18 @@ var freeParseInt = parseInt;
  * // => 3
  */
 function toNumber(value) {
+  if (typeof value == 'number') {
+    return value;
+  }
+  if (isSymbol(value)) {
+    return NAN;
+  }
   if (isObject(value)) {
     var other = isFunction(value.valueOf) ? value.valueOf() : value;
     value = isObject(other) ? (other + '') : other;
   }
   if (typeof value != 'string') {
-    return value === 0 ? value : +value;
+    return value === 0 ?  value : +value;
   }
   value = value.replace(reTrim, '');
   var isBinary = reIsBinary.test(value);