[js] fix documentation on By.js
Fixes
@@ -176,9 +176,12 @@ class By {
}
/**
- * Locates an elements by evaluating a
- * {@linkplain webdriver.WebDriver#executeScript JavaScript expression}.
- * The result of this expression must be an element or list of elements.
+ * Locates elements by evaluating a `script` that defines the body of
+ * a {@linkplain webdriver.WebDriver#executeScript JavaScript function}.
+ * The return value of this function must be an element or an array-like
+ * list of elements. When this locator returns a list of elements, but only
+ * one is expected, the first element in this list will be used as the
+ * single element value.
*
* @param {!(string|Function)} script The script to execute.
* @param {...*} var_args The arguments to pass to the script.
