add check that the shared page is fully displayed (mozilla-mobile#377)

Author: No-Jun Park

focus-ios/XCUITest/OpenInFocusTest.swift

@@ -21,13 +21,16 @@ class OpenInFocusTest : BaseTestCase {
         waitforExistence(element: app.textFields["URLBar.urlText"]) // wait for app.label
         let sharedExtName = app.label.contains("Klar") ? "Firefox Klar" : "Firefox Focus" as String
 
+        XCUIDevice.shared().press(.home)
+        let springboard = XCUIApplication(privateWithPath: nil, bundleID: "com.apple.springboard")!
+        waitforExistence(element: springboard.scrollViews.otherElements.icons[sharedExtName])
+
         let safariApp = XCUIApplication(privateWithPath: nil, bundleID: "com.apple.mobilesafari")!
         safariApp.launchArguments = ["-u", "https://www.mozilla.org/en-US/"]
         safariApp.launch()
-
+        
         safariApp.buttons["Share"].tap()
         safariApp.buttons["More"].tap()
-        
         safariApp.tables.cells.containing(.staticText, identifier:sharedExtName).children(matching: .switch).matching(identifier: sharedExtName).element(boundBy: 0).tap()
         safariApp.navigationBars["Activities"].buttons["Done"].tap()
         safariApp.buttons[sharedExtName].tap()
@@ -36,5 +39,6 @@ class OpenInFocusTest : BaseTestCase {
         let addressBarField = focusApp.textFields["URLBar.urlText"]
 
         waitForValueContains(element: addressBarField, value: "https://www.mozilla.org/en-US/")
+        waitforExistence(element: focusApp.buttons["ERASE"])  // check site is fully loaded
     }
 }