Created methods to surface zone memory information for each isolate and thread in JSON.

runtime/vm/thread.h

Index: runtime/vm/thread.h
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index a9fb55faaa400ba83db8891442d38e261236a283..2530c21755391f16ef36b089651fad6889872bfd 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -37,6 +37,7 @@ class Library;
 class LongJumpScope;
 class Object;
 class OSThread;
+class JSONObject;
 class PcDescriptors;
 class RawBool;
 class RawObject;
@@ -646,6 +647,10 @@ class Thread : public BaseThread {
 
   void InitVMConstants();
 
+#if defined(DEBUG)

[zra, 2016/12/08 18:54:13]

Don't we also want this in a RELEASE build? Should this be #ifndef PRODUCT?

[bkonyi, 2016/12/08 20:58:32]

Done.

+  void PrintJSON(JSONStream* stream, bool ref = true) const;

[zra, 2016/12/08 18:54:13]

Is this ever called with anything overriding the default for 'ref'? If not,
let's remove the argument.

[bkonyi, 2016/12/08 20:58:32]

Done.

+#endif
+
  private:
   template <class T>
   T* AllocateReusableHandle();