Fixed bad calculations for determining total allocated size of a zone.

runtime/vm/zone.cc

Index: runtime/vm/zone.cc
diff --git a/runtime/vm/zone.cc b/runtime/vm/zone.cc
index 2632f3a3e5436f8a19b6522880d09741a4fffaec..36e962260dd30ed433c67ff89812392ece46ec04 100644
--- a/runtime/vm/zone.cc
+++ b/runtime/vm/zone.cc
@@ -136,6 +136,22 @@ intptr_t Zone::SizeInBytes() const {
 }
 
 
+intptr_t Zone::CapacityInBytes() const {
+  intptr_t size = 0;
+  for (Segment* s = large_segments_; s != NULL; s = s->next()) {
+    size += s->size();
+  }
+  if (head_ == NULL) {
+    return size + initial_buffer_.size();
+  }
+  size += initial_buffer_.size();
+  for (Segment* s = head_; s != NULL; s = s->next()) {
+    size += s->size();
+  }
+  return size;
+}
+
+
 uword Zone::AllocateExpand(intptr_t size) {
   ASSERT(size >= 0);
   if (FLAG_trace_zones) {
@@ -263,8 +279,8 @@ char* Zone::VPrint(const char* format, va_list args) {
 #ifndef PRODUCT
 void Zone::PrintJSON(JSONStream* stream) const {
   JSONObject jsobj(stream);
-  intptr_t capacity = SizeInBytes();
-  intptr_t used_size = UsedSizeInBytes();
+  intptr_t capacity = CapacityInBytes();
+  intptr_t used_size = SizeInBytes();
   jsobj.AddProperty("type", "_Zone");
   jsobj.AddProperty("capacity", capacity);
   jsobj.AddProperty("used", used_size);