Include PUB_CACHE when invoking build.dart too.

tools/testing/dart/test_suite.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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 1772 matching lines @@
         commands.add(CommandBuilder.instance.getPubCommand(
             "get", pubPath, checkoutDir, cacheDir));
 
         bool containsWebDirectory = dirExists(directoryPath.append('web'));
         bool containsBuildDartFile =
             fileExists(directoryPath.append('build.dart'));
         if (containsBuildDartFile) {
           var dartBinary = new File(dartVmBinaryFileName).absolute.path;
 
           commands.add(CommandBuilder.instance.getProcessCommand(
-              "custom_build", dartBinary, ['build.dart'], null,
-              checkoutDir));
+              "custom_build", dartBinary, ['build.dart'],
+              {'PUB_CACHE': cacheDir}, checkoutDir));
 
           // We only try to deploy the application if it's a webapp.
           if (containsWebDirectory) {
             commands.add(CommandBuilder.instance.getProcessCommand(
-                 "custom_deploy", dartBinary, ['build.dart', '--deploy'], null,
-                 checkoutDir));
+                 "custom_deploy", dartBinary, ['build.dart', '--deploy'],
+                 {'PUB_CACHE': cacheDir}, checkoutDir));
           }
         } else if (containsWebDirectory)  {
           commands.add(CommandBuilder.instance.getPubCommand(
              "build", pubPath, checkoutDir, cacheDir));
         }
 
         // Enqueue TestCase
         var testCase = new TestCase(displayName,
             commands, configuration, testExpectations.expectations(testName));
         enqueueNewTestCase(testCase);
@@ skipping 411 matching lines @@
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
  * $compileErrorSkip tests are skipped on browsers due to compile-time error
 """;
     print(report);
   }
 }