All strong mode cleaning of dart2js.

tests/compiler/dart2js/deferred_mirrors_test.dart

 // Copyright (c) 2014, 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.
 
 // Test of the graph segmentation algorithm used by deferred loading
 // to determine which elements can be deferred and which libraries
 // much be included in the initial download (loaded eagerly).
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'memory_compiler.dart';
-import 'package:compiler/src/compiler.dart' as dart2js;
 
 Future runTest(String mainScript, test) async {
   CompilationResult result = await runCompiler(
       entryPoint: Uri.parse(mainScript),
       memorySourceFiles: MEMORY_SOURCE_FILES);
   test(result.compiler);
 }
 
 lookupLibrary(compiler, name) {
   return compiler.libraryLoader.lookupLibrary(Uri.parse(name));
@@ skipping 44 matching lines @@
     Expect.notEquals(outputUnitForElement(main), outputUnitForElement(foo));
     Expect.equals(outputUnitForElement(main), outputUnitForElement(C));
   });
   await runTest('memory:main4.dart', (compiler) {
     var main = compiler.frontendStrategy.elementEnvironment.mainFunction;
     Expect.isNotNull(main, "Could not find 'main'");
     compiler.deferredLoadTask.onResolutionComplete(
         main, compiler.resolutionWorldBuilder.closedWorldForTesting);
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
 
-    var mainLib = lookupLibrary(compiler, "memory:main4.dart");
-    var lib4 = lookupLibrary(compiler, "memory:lib4.dart");
+    lookupLibrary(compiler, "memory:main4.dart");
+    lookupLibrary(compiler, "memory:lib4.dart");
     var lib5 = lookupLibrary(compiler, "memory:lib5.dart");
     var lib6 = lookupLibrary(compiler, "memory:lib6.dart");
     var foo5 = lib5.find("foo");
     var foo6 = lib6.find("foo");
 
     Expect.notEquals(outputUnitForElement(main), outputUnitForElement(foo5));
     Expect.equals(outputUnitForElement(foo5), outputUnitForElement(foo6));
   });
 }
 
@@ skipping 105 matching lines @@
 library lib5;
 
 foo() {}
 """,
   "lib6.dart": """
 library lib6;
 
 foo() {}
 """,
 };