[hot reload] Ensure old class table is also freed on success.

runtime/vm/isolate_reload.cc

Index: runtime/vm/isolate_reload.cc
diff --git a/runtime/vm/isolate_reload.cc b/runtime/vm/isolate_reload.cc
index 414d09381d200b545b70c0a38051459728be7825..76882ec991a6018831d7ece9a27b9375b4425567 100644
--- a/runtime/vm/isolate_reload.cc
+++ b/runtime/vm/isolate_reload.cc
@@ -473,7 +473,9 @@ IsolateReloadContext::IsolateReloadContext(Isolate* isolate, JSONStream* js)
 }
 
 
-IsolateReloadContext::~IsolateReloadContext() {}
+IsolateReloadContext::~IsolateReloadContext() {
+  ASSERT(saved_class_table_ == NULL);
+}
 
 
 void IsolateReloadContext::ReportError(const Error& error) {
@@ -1149,6 +1151,9 @@ void IsolateReloadContext::Commit() {
   if (HasInstanceMorphers()) {
     // Perform shape shifting of instances if necessary.
     MorphInstances();
+  } else {
+    free(saved_class_table_);
+    saved_class_table_ = NULL;
   }
 
 #ifdef DEBUG