TBR: Removing the config assertions again; they still seem to be causing problems.

pkg/unittest/lib/src/config.dart

Index: pkg/unittest/lib/src/config.dart
===================================================================
--- pkg/unittest/lib/src/config.dart	(revision 19088)
+++ pkg/unittest/lib/src/config.dart	(working copy)
@@ -52,8 +52,6 @@
    * a test suite.
    */
   void onTestStart(TestCase testCase) {
-    assert(testCase != null);
-    assert(_currentTestCase == null);
     _currentTestCase = testCase;
   }
 
@@ -62,8 +60,6 @@
    * a test suite.
    */
   void onTestResult(TestCase testCase) {
-    assert(testCase != null);
-    assert(_currentTestCase == null || _currentTestCase == testCase);
     _currentTestCase = null;
   }