Avoid repeated declaration of the same loop variable.

lib/compiler/implementation/dart2js.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.
 
 #library('dart2js');
 
 #import('dart:io');
 #import('dart:uri');
 #import('dart:utf');
 
@@ skipping 115 matching lines @@
     }
     String source;
     try {
       source = readAll(uriPathToNative(uri.path));
     } catch (FileIOException ex) {
       throw 'Error: Cannot read "${relativize(cwd, uri)}" (${ex.osError}).';
     }
     dartBytesRead += source.length;
     sourceFiles[uri.toString()] =
       new SourceFile(relativize(cwd, uri), source);
-    Completer<String> completer = new Completer<String>();
-    completer.complete(source);
-    return completer.future;
+    return new Future.immediate(source);
   }
 
   void info(var message) {
     if (verbose) print('${colors.green("info:")} $message');
   }
 
   bool isAborting = false;
 
   void handler(Uri uri, int begin, int end, String message, bool fatal) {
     if (isAborting) return;
@@ skipping 160 matching lines @@
     } catch (var ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }