WIP: Add webdriver.By.Hash

`webdriver.By.Hash` is a Closure Llibrary style type alias.
If we assign `webdriver.By.Hash`, we get an `undefined`.
I think the assignment should have an error, because it have no
meanings.

selenium-webdriver/selenium-webdriver.d.ts

@@ -4783,6 +4783,40 @@ declare module webdriver {
 
     var By: ILocatorStrategy;
 
+    module By {
+        /**
+         * Short-hand expressions for the primary element locator strategies.
+         * For example the following two statements are equivalent:
+         *
+         *     var e1 = driver.findElement(webdriver.By.id('foo'));
+         *     var e2 = driver.findElement({id: 'foo'});
+         *
+         * Care should be taken when using JavaScript minifiers (such as the
+         * Closure compiler), as locator hashes will always be parsed using
+         * the un-obfuscated properties listed.
+         *
+         * @typedef {(
+         *     {className: string}|
+         *     {css: string}|
+         *     {id: string}|
+         *     {js: string}|
+         *     {linkText: string}|
+         *     {name: string}|
+         *     {partialLinkText: string}|
+         *     {tagName: string}|
+         *     {xpath: string})}
+         */
+        type Hash = {className: string}|
+            {css: string}|
+            {id: string}|
+            {js: string}|
+            {linkText: string}|
+            {name: string}|
+            {partialLinkText: string}|
+            {tagName: string}|
+            {xpath: string};
+    }
+
     /**
      * An element locator.
      */