Bump to v4.7.0.

_createMathOperation.js

@@ -0,0 +1,30 @@
+define([], function() {
+
+  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
+  var undefined;
+
+  /**
+   * Creates a function that performs a mathematical operation on two values.
+   *
+   * @private
+   * @param {Function} operator The function to perform the operation.
+   * @returns {Function} Returns the new mathematical operation function.
+   */
+  function createMathOperation(operator) {
+    return function(value, other) {
+      var result;
+      if (value === undefined && other === undefined) {
+        return 0;
+      }
+      if (value !== undefined) {
+        result = value;
+      }
+      if (other !== undefined) {
+        result = result === undefined ? other : operator(result, other);
+      }
+      return result;
+    };
+  }
+
+  return createMathOperation;
+});