fix(protractor): export class definitions under the protractor namespace (#3393)

closes #3377

Author: cnishina

lib/ptor.ts

@@ -15,6 +15,15 @@ export namespace protractor {
   export let wrapDriver: Function;
   export let ExpectedConditions: ProtractorExpectedConditions;
 
+  // Export the protractor classes
+  export let Browser = require('./browser').Browser;
+  export let ElementFinder = require('./element').ElementFinder;
+  export let ElementArrayFinder = require('./element').ElementArrayFinder;
+  export let ElementHelper = require('./browser').ElementHelper;
+  export let ProtractorBy = require('./locators').ProtractorBy;
+  export let ProtractorExpectedConditions =
+      require('./expectedConditions').ProtractorExpectedConditions;
+
   // Define selenium webdriver imports.
   export let promise = webdriver.promise;
   export let WebElement = webdriver.WebElement;