Tweak for escaping in instrumentation.

pkg/analyzer/test/instrumentation/instrumentation_test.dart

Index: pkg/analyzer/test/instrumentation/instrumentation_test.dart
diff --git a/pkg/analyzer/test/instrumentation/instrumentation_test.dart b/pkg/analyzer/test/instrumentation/instrumentation_test.dart
index 332531817362963ffc775498455fb633fe6e5ec8..9a3d409e633cc182d90fe8a72eaaab5c512821b3 100644
--- a/pkg/analyzer/test/instrumentation/instrumentation_test.dart
+++ b/pkg/analyzer/test/instrumentation/instrumentation_test.dart
@@ -38,6 +38,13 @@ class InstrumentationServiceTest extends ReflectiveTestCase {
     assertNormal(server, InstrumentationService.TAG_ERROR, 'Error::message');
   }
 
+  void test_logError_withLeadingColon() {
+    TestInstrumentationServer server = new TestInstrumentationServer();
+    InstrumentationService service = new InstrumentationService(server);
+    service.logError(':a:bb');
+    assertNormal(server, InstrumentationService.TAG_ERROR, '::a::bb');
+  }
+
   void test_logException_noTrace() {
     TestInstrumentationServer server = new TestInstrumentationServer();
     InstrumentationService service = new InstrumentationService(server);