enable lint prefer_foreach (#12674) * enable lint prefer_foreach * fix tests

diff --git a/packages/flutter_tools/lib/src/asset.dart b/packages/flutter_tools/lib/src/asset.dart
index 92bc656..9dc1d6d 100644
--- a/packages/flutter_tools/lib/src/asset.dart
+++ b/packages/flutter_tools/lib/src/asset.dart

@@ -194,9 +194,7 @@
 
   void dump() {
     printTrace('Dumping AssetBundle:');
-    for (String archivePath in entries.keys.toList()..sort()) {
-      printTrace(archivePath);
-    }
+    (entries.keys.toList()..sort()).forEach(printTrace);
   }
 }
 

diff --git a/packages/flutter_tools/lib/src/base/net.dart b/packages/flutter_tools/lib/src/base/net.dart
index 1d9adfb..52ef656 100644
--- a/packages/flutter_tools/lib/src/base/net.dart
+++ b/packages/flutter_tools/lib/src/base/net.dart

@@ -55,8 +55,7 @@
   printTrace('Received response from server, collecting bytes...');
   try {
     final BytesBuilder responseBody = new BytesBuilder(copy: false);
-    await for (List<int> chunk in response)
-      responseBody.add(chunk);
+    await response.forEach(responseBody.add);
     return responseBody.takeBytes();
   } on IOException catch (error) {
     printTrace('Download error: $error');

diff --git a/packages/flutter_tools/lib/src/base/utils.dart b/packages/flutter_tools/lib/src/base/utils.dart
index af7b8b8..2a4fee1 100644
--- a/packages/flutter_tools/lib/src/base/utils.dart
+++ b/packages/flutter_tools/lib/src/base/utils.dart

@@ -142,10 +142,8 @@
 
     _items = updatedSet;
 
-    for (T item in addedItems)
-      _addedController.add(item);
-    for (T item in removedItems)
-      _removedController.add(item);
+    addedItems.forEach(_addedController.add);
+    removedItems.forEach(_removedController.add);
   }
 
   /// Close the streams.

diff --git a/packages/flutter_tools/lib/src/compile.dart b/packages/flutter_tools/lib/src/compile.dart
index 4299b8b..7d4912f 100644
--- a/packages/flutter_tools/lib/src/compile.dart
+++ b/packages/flutter_tools/lib/src/compile.dart

@@ -131,8 +131,7 @@
 
     final String inputKey = new Uuid().generateV4();
     _server.stdin.writeln('recompile $inputKey');
-    for (String invalidatedFile in invalidatedFiles)
-      _server.stdin.writeln(invalidatedFile);
+    invalidatedFiles.forEach(_server.stdin.writeln);
     _server.stdin.writeln(inputKey);
 
     return stdoutHandler.outputFilename.future;

diff --git a/packages/flutter_tools/lib/src/devfs.dart b/packages/flutter_tools/lib/src/devfs.dart
index e1b1e6e..f94de19 100644
--- a/packages/flutter_tools/lib/src/devfs.dart
+++ b/packages/flutter_tools/lib/src/devfs.dart

@@ -478,8 +478,7 @@
       }
       // No need to send source files because all compilation is done on the
       // host and result of compilation is single kernel file.
-      for (Uri fileUri in filesUris)
-        dirtyEntries.remove(fileUri);
+      filesUris.forEach(dirtyEntries.remove);
       printTrace('Compiling dart to kernel with ${invalidatedFiles.length} updated files');
       final String compiledBinary = fullRestart
         ? await compile(