Install prebuilt iOS applications before running them (#7000)

diff --git a/packages/flutter_tools/lib/src/ios/devices.dart b/packages/flutter_tools/lib/src/ios/devices.dart
index 396582f..9970159 100644
--- a/packages/flutter_tools/lib/src/ios/devices.dart
+++ b/packages/flutter_tools/lib/src/ios/devices.dart
@@ -198,6 +198,9 @@
         printError('');
         return new LaunchResult.failed();
       }
+    } else {
+      if (!installApp(app))
+        return new LaunchResult.failed();
     }
 
     // Step 2: Check that the application exists at the specified path.
diff --git a/packages/flutter_tools/lib/src/ios/simulators.dart b/packages/flutter_tools/lib/src/ios/simulators.dart
index 2cb71bd..6d405c8 100644
--- a/packages/flutter_tools/lib/src/ios/simulators.dart
+++ b/packages/flutter_tools/lib/src/ios/simulators.dart
@@ -426,6 +426,9 @@
       } on ToolExit {
         return new LaunchResult.failed();
       }
+    } else {
+      if (!installApp(app))
+        return new LaunchResult.failed();
     }
 
     ProtocolDiscovery observatoryDiscovery;