Add dead CodeRegionTable for tracking overwritten Dart code

runtime/bin/vmservice/client/lib/src/service/object.dart

Index: runtime/bin/vmservice/client/lib/src/service/object.dart
diff --git a/runtime/bin/vmservice/client/lib/src/service/object.dart b/runtime/bin/vmservice/client/lib/src/service/object.dart
index 6d14e12e37db615417a6e8b3eaf8d2e0994c742a..65a6ae0a3510a6c452b5063e1a104d7cca1d1220 100644
--- a/runtime/bin/vmservice/client/lib/src/service/object.dart
+++ b/runtime/bin/vmservice/client/lib/src/service/object.dart
@@ -49,9 +49,10 @@ class Isolate extends ServiceObject {
   void processProfile(ServiceMap profile) {
     assert(profile.serviceType == 'Profile');
     var codeTable = new List<Code>();
-    var profileCodes = profile['codes'];
-    for (var profileCode in profileCodes) {
-      Code code = profileCode['code'];
+    var codeRegions = profile['codes'];
+    for (var codeRegion in codeRegions) {
+      Code code = codeRegion['code'];
+      assert(code != null);
       codeTable.add(code);
     }
     _codes._resetProfileData();
@@ -493,8 +494,8 @@ class Code extends ServiceObject {
   void updateProfileData(Map profileData,
                          List<Code> codeTable,
                          int sampleCount) {
-    // Assert we have a ProfileCode entry.
-    assert(profileData['type'] == 'ProfileCode');
+    // Assert we have a CodeRegion entry.
+    assert(profileData['type'] == 'CodeRegion');
     // Assert we are handed profile data for this code object.
     assert(profileData['code'] == this);
     totalSamplesInProfile = sampleCount;