Added support for skipping redundant dart2js compilations.

tools/testing/dart/test_progress.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("test_progress");
 
 #import("dart:io");
 #import("test_runner.dart");
 #import("test_suite.dart");
 #import("status_file_parser.dart");
@@ skipping 35 matching lines @@
   }
 
   void done(TestCase test) {
     if (test.isFlaky && test.lastCommandOutput.result != PASS) {
       var buf = new StringBuffer();
       for (var l in _buildFailureOutput(test)) {
         buf.add("$l\n");
       }
       _appendToFlakyFile(buf.toString());
     }
+    for (var commandOutput in test.commandOutputs.values) {
+      if (commandOutput.compilationSkipped)
+        _skippedCompilations++;
+    }
 
     if (test.lastCommandOutput.unexpectedOutput) {
       _failedTests++;
       _printFailureOutput(test);
     } else {
       _passedTests++;
     }
     _printDoneProgress(test);
     // If we need to print timing information we hold on to all completed
     // tests.
     if (_printTiming) _tests.add(test);
   }
 
   void allTestsKnown() {
     if (!_allTestsKnown) SummaryReport.printReport();
     _allTestsKnown = true;
   }
 
+  void _printSkippedCompilationInfo() {
+    if (_skippedCompilations > 0) {
+      print('\n$_skippedCompilations compilations were skipped because '
+            'the previous output was already up to date\n');
+    }
+  }
+
   void _printTimingInformation() {
     if (_printTiming) {
       // TODO: We should take all the commands into account
       Duration d = (new Date.now()).difference(_startTime);
       print('\n--- Total time: ${_timeString(d)} ---');
       _tests.sort((a, b) {
         Duration aDuration = a.lastCommandOutput.time;
         Duration bDuration = b.lastCommandOutput.time;
         return bDuration.inMilliseconds - aDuration.inMilliseconds;
       });
       for (int i = 0; i < 20 && i < _tests.length; i++) {
         var name = _tests[i].displayName;
         var duration = _tests[i].lastCommandOutput.time;
         var configuration = _tests[i].configurationString;
         print('${duration} - $configuration $name');
       }
     }
   }
 
   void allDone() {
     _printFailureSummary();
     _printStatus();
+    _printSkippedCompilationInfo();
     _printTimingInformation();
     stdout.close();
     stderr.close();
     if (_failedTests > 0) exit(1);
   }
 
   void _printStartProgress(TestCase test) {}
   void _printDoneProgress(TestCase test) {}
 
   String _pad(String s, int length) {
@@ skipping 112 matching lines @@
     fd.closeSync();
   }
 
   int get numFailedTests => _failedTests;
 
   int _completedTests() => _passedTests + _failedTests;
 
   int _foundTests = 0;
   int _passedTests = 0;
   int _failedTests = 0;
+  int _skippedCompilations = 0;
   bool _allTestsKnown = false;
   Date _startTime;
   bool _printTiming;
   List<TestCase> _tests;
   List<String> _failureSummary;
 }
 
 
 class SilentProgressIndicator extends ProgressIndicator {
   SilentProgressIndicator(Date startTime, bool printTiming)
       : super(startTime, printTiming);
   void testAdded() { }
   void start(TestCase test) { }
   void done(TestCase test) { }
   void _printStartProgress(TestCase test) { }
   void _printDoneProgress(TestCase test) { }
   void allTestsKnown() { }
   void allDone() { }
 }
 
 abstract class CompactIndicator extends ProgressIndicator {
   CompactIndicator(Date startTime, bool printTiming)
       : super(startTime, printTiming);
 
   void allDone() {
     stdout.write('\n'.charCodes);
     _printFailureSummary();
+    _printSkippedCompilationInfo();
     _printTimingInformation();
     if (_failedTests > 0) {
       // We may have printed many failure logs, so reprint the summary data.
       _printProgress();
       print('');
     }
     stdout.close();
     stderr.close();
     if (_failedTests > 0) exit(1);
   }
@@ skipping 198 matching lines @@
       print('');
       print('$config:');
       statuses.sort((a, b) => a.compareTo(b));
       for (String status in statuses) {
         print('  $status');
       }
     });
     _printStatus();
   }
 }