Bump to v3.10.0.

internal/mergeDefaults.js

@@ -0,0 +1,19 @@
+define(['../object/merge'], function(merge) {
+
+  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
+  var undefined;
+
+  /**
+   * Used by `_.defaultsDeep` to customize its `_.merge` use.
+   *
+   * @private
+   * @param {*} objectValue The destination object property value.
+   * @param {*} sourceValue The source object property value.
+   * @returns {*} Returns the value to assign to the destination object.
+   */
+  function mergeDefaults(objectValue, sourceValue) {
+    return objectValue === undefined ? sourceValue : merge(objectValue, sourceValue, mergeDefaults);
+  }
+
+  return mergeDefaults;
+});