diff --git a/examples/material_gallery/lib/demo/tabs_fab_demo.dart b/examples/material_gallery/lib/demo/tabs_fab_demo.dart
index cb5556a13b..def007dfcd 100644
--- a/examples/material_gallery/lib/demo/tabs_fab_demo.dart
+++ b/examples/material_gallery/lib/demo/tabs_fab_demo.dart
@@ -31,7 +31,7 @@ class TabsFabDemo extends StatefulWidget {
 }
 
 class _TabsFabDemoState extends State<TabsFabDemo> {
-  final GlobalKey scaffoldKey = new GlobalKey();
+  final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
   final List<_Page> pages = <_Page>[
     new _Page(label: 'Blue', colors: Colors.indigo, icon: Icons.add),
     new _Page(label: 'Eco', colors: Colors.green, icon: Icons.create),
diff --git a/packages/flutter/lib/src/widgets/scrollable.dart b/packages/flutter/lib/src/widgets/scrollable.dart
index e335a64785..472f99e25a 100644
--- a/packages/flutter/lib/src/widgets/scrollable.dart
+++ b/packages/flutter/lib/src/widgets/scrollable.dart
@@ -546,7 +546,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
       config.onScrollEnd(_scrollOffset);
   }
 
-  final GlobalKey _gestureDetectorKey = new GlobalKey();
+  final GlobalKey<RawGestureDetectorState> _gestureDetectorKey = new GlobalKey<RawGestureDetectorState>();
 
   @override
   Widget build(BuildContext context) {
diff --git a/packages/flutter/test/widget/tooltip_test.dart b/packages/flutter/test/widget/tooltip_test.dart
index dd191defb7..a490b1ff66 100644
--- a/packages/flutter/test/widget/tooltip_test.dart
+++ b/packages/flutter/test/widget/tooltip_test.dart
@@ -10,6 +10,21 @@ import 'package:test/test.dart';
 
 import 'test_semantics.dart';
 
+// This file uses "as dynamic" in a few places to defeat the static
+// analysis. In general you want to avoid using this style in your
+// code, as it will cause the analyzer to be unable to help you catch
+// errors.
+//
+// In this case, we do it because we are trying to call internal
+// methods of the tooltip code in order to test it. Normally, the
+// state of a tooltip is a private class, but by using a GlobalKey we
+// can get a handle to that object and by using "as dynamic" we can
+// bypass the analyzer's type checks and call methods that we aren't
+// supposed to be able to know about.
+//
+// It's ok to do this in tests, but you really don't want to do it in
+// production code.
+
 void main() {
   test('Does tooltip end up in the right place - top left', () {
     testWidgets((WidgetTester tester) {
@@ -47,7 +62,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       /********************* 800x600 screen
@@ -101,7 +116,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       /********************* 800x600 screen
@@ -157,7 +172,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       // we try to put it here but it doesn't fit:
@@ -224,7 +239,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       /********************* 800x600 screen
@@ -279,7 +294,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       /********************* 800x600 screen
@@ -336,7 +351,7 @@ void main() {
           ]
         )
       );
-      key.currentState.showTooltip();
+      (key.currentState as dynamic).showTooltip(); // before using "as dynamic" in your code, see note top of file
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
 
       /********************* 800x600 screen
@@ -404,7 +419,8 @@ void main() {
       expect(client.updates[1], isNull);
       client.updates.clear();
 
-      key.currentState.showTooltip(); // this triggers a rebuild of the semantics because the tree changes
+      // before using "as dynamic" in your code, see note top of file
+      (key.currentState as dynamic).showTooltip(); // this triggers a rebuild of the semantics because the tree changes
 
       tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
       expect(client.updates.length, equals(2));
diff --git a/packages/flutter_tools/lib/src/commands/build_ios.dart b/packages/flutter_tools/lib/src/commands/build_ios.dart
index e673513453..0d46b4c678 100644
--- a/packages/flutter_tools/lib/src/commands/build_ios.dart
+++ b/packages/flutter_tools/lib/src/commands/build_ios.dart
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import '../application_package.dart';
 import '../build_configuration.dart';
@@ -11,8 +10,6 @@ import '../globals.dart';
 import '../ios/mac.dart';
 import '../runner/flutter_command.dart';
 
-import 'package:path/path.dart' as path;
-
 class BuildIOSCommand extends FlutterCommand {
   BuildIOSCommand() {
     argParser.addFlag('simulator', help: 'Build for the iOS simulator instead of the device.');