Do some housekeeping in tools/testing/dart

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index 4aa99f4e044a710bf330ca70044baaea0df790e0..cab1824a28c92ab24acbdcdc73889048406b9730 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -1079,7 +1079,6 @@ class StandardTestSuite extends TestSuite {
       List<String> otherResources = info.optionsFromFile['otherResources'];
       for (String name in otherResources) {
         Path namePath = new Path(name);
-        String fileName = namePath.filename;
         Path fromPath = info.filePath.directoryPath.join(namePath);
         new File('$tempDir/$name').parent.createSync(recursive: true);
         new File(fromPath.toNativePath()).copySync('$tempDir/$name');
@@ -1171,6 +1170,7 @@ class StandardTestSuite extends TestSuite {
     // Unreachable
     print("Cannot create URL for path $file. Not in build or dart directory.");
     exit(1);
+    return null;
   }
 
   Uri _getUriForBrowserTest(String pathComponent, String subtestName) {