Export Locator (#4459)

* Export Locator

by.cssContainingText returns a ProtractorLocator, but Locator couldn't be imported in a TS file.

* Update index.ts

* Update index.ts

* Update index.ts

* Update index.ts

* Update index.ts

* Update index.ts

Author: barrtender

Diff for: lib/index.ts

@@ -1,7 +1,7 @@
 import {ElementHelper, ProtractorBrowser} from './browser';
 import {ElementArrayFinder, ElementFinder} from './element';
 import {ProtractorExpectedConditions} from './expectedConditions';
-import {ProtractorBy} from './locators';
+import {Locator, ProtractorBy} from './locators';
 import {PluginConfig, ProtractorPlugin} from './plugins';
 import {Ptor} from './ptor';
 
@@ -12,7 +12,7 @@ export {ElementHelper, ProtractorBrowser} from './browser';
 export {Config} from './config';
 export {ElementArrayFinder, ElementFinder} from './element';
 export {ProtractorExpectedConditions} from './expectedConditions';
-export {ProtractorBy} from './locators';
+export {Locator, ProtractorBy} from './locators';
 export {Ptor} from './ptor';
 export {Runner} from './runner';