fix(isElementPresent): for un-wrapped WebElements, browser.isElementPresent was broken

Closes angular#3864

Author: sjelin

lib/browser.ts

@@ -589,10 +589,16 @@ export class ProtractorBrowser extends Webdriver {
    * @returns {!webdriver.promise.Promise} A promise that will resolve to whether
    *     the element is present on the page.
    */
-  isElementPresent(locatorOrElement: ProtractorBy|WebElement): wdpromise.Promise<any> {
-    let element =
-        ((locatorOrElement as any).isPresent) ? locatorOrElement : this.element(locatorOrElement);
-    return (element as any).isPresent();
+  isElementPresent(locatorOrElement: Locator|WebElement): wdpromise.Promise<any> {
+    let element: ElementFinder;
+    if ((locatorOrElement as any).isPresent) {
+      element = locatorOrElement as ElementFinder;
+    } else if (locatorOrElement instanceof WebElement) {
+      element = ElementFinder.fromWebElement_(this, locatorOrElement);
+    } else {
+      element = this.element(locatorOrElement);
+    }
+    return element.isPresent();
   }
 
   /**

lib/element.ts

@@ -846,7 +846,7 @@ export class ElementFinder extends WebdriverWebElement {
   }
   [key: string]: any;
 
-  static fromWebElement_(browser: ProtractorBrowser, webElem: WebElement, locator: Locator):
+  static fromWebElement_(browser: ProtractorBrowser, webElem: WebElement, locator?: Locator):
       ElementFinder {
     let getWebElements = () => {
       return wdpromise.fulfilled([webElem]);