Moved isolate high watermark calculations into the Observatory client.

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index ccc9054597b92b533b9fa16d6c53f5a9fdc20d47..4f93396c98064761341fa796e90b0145c1b461b8 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -1645,10 +1645,12 @@ class Isolate extends ServiceObjectOwner implements M.Isolate {
       threads.addAll(map['_threads']);
     }
 
-    _memoryHighWatermark = int.parse(map['_memoryHighWatermark']);
+    print("Threads:");

[Cutch, 2017/01/25 00:04:46]

remove debug code

[bkonyi, 2017/01/25 00:27:13]

Done.

+    print(map['_threads']);
 
-    if (map['threads'] != null) {
-      threads.addAll(map['threads']);
+    _memoryHighWatermark = 0;
+    for (var i = 0; i < threads.length; i++) {
+      _memoryHighWatermark += threads[i].memoryHighWatermark;

[Cutch, 2017/01/25 00:04:46]

This is different than the C code which sums the threads and then checks if it
is bigger than the pre-existing high water mark.

[bkonyi, 2017/01/25 00:27:13]

Done.

     }
 
     _numZoneHandles = map['_numZoneHandles'];