Add temporary directory for dartc compilation of tests.

tools/test.dart

Index: tools/test.dart
diff --git a/tools/test.dart b/tools/test.dart
index c776db0c0139b55decc073fc071f3448e58b40e6..3990323ad2819a2058c6560752d157022df2cbee 100755
--- a/tools/test.dart
+++ b/tools/test.dart
@@ -41,6 +41,7 @@ main() {
   var verbose = firstConf['verbose'];
   var printTiming = firstConf['time'];
   var listTests = firstConf['list'];
+  var keepGeneratedTests = firstConf['keep-generated-tests'];
 
   var configurationIterator = configurations.iterator();
   bool enqueueConfiguration(ProcessQueue queue) {
@@ -113,6 +114,7 @@ main() {
                                startTime,
                                printTiming,
                                enqueueConfiguration,
-                               verbose: verbose,
-                               listTests: listTests);
+                               verbose,
+                               listTests,
+                               keepGeneratedTests);
 }