Fix more strong mode errors and warnings.

lib/src/utils.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 import 'dart:async';
 import "dart:convert";
 import 'dart:io';
 import 'dart:math' as math;
 
@@ skipping 612 matching lines @@
 /// Takes a simple data structure (composed of [Map]s, [Iterable]s, scalar
 /// objects, and [Future]s) and recursively resolves all the [Future]s contained
 /// within.
 ///
 /// Completes with the fully resolved structure.
 Future/*<T>*/ awaitObject/*<T>*/(/*=T*/ object) async {
   // Unroll nested futures.
   if (object is Future) return await awaitObject(await object);
 
   if (object is Iterable) {
-    // TODO(nweiz): Remove the unnecessary as check when sdk#26965 is fixed.
-    return await Future.wait((object as Iterable).map(awaitObject))
-        as List/*=T*/;
+    return await Future.wait(object.map(awaitObject)) as List/*=T*/;
   }
 
   if (object is Map) {
-    // TODO(nweiz): Remove the unnecessary as check when sdk#26965 is fixed.
-    var oldMap = object as Map;
     var newMap = {};
-    await Future.wait(oldMap.keys.map((key) async {
-      newMap[key] = await awaitObject(await oldMap[key]);
+    await Future.wait(object.keys.map((key) async {
+      newMap[key] = await awaitObject(await object[key]);
     }));
     return newMap as Map/*=T*/;
   }
 
   return object;
 }
 
 /// Whether "special" strings such as Unicode characters or color escapes are
 /// safe to use.
 ///
@@ skipping 129 matching lines @@
   } else {
     throw new ApplicationException(message);
   }
 }
 
 /// Throw a [DataException] with [message] to indicate that the command has
 /// failed because of invalid input data.
 ///
 /// This will report the error and cause pub to exit with [exit_codes.DATA].
 void dataError(String message) => throw new DataException(message);