Revert "Fix use-after-free in isolate reload."

This reverts commit 16e577741d.

TBR=johnmccutchan@google.com,

BUG=

Review URL: https://codereview.chromium.org/2162113002 .

runtime/vm/isolate.cc

@@ -1095,8 +1095,6 @@ void Isolate::ReloadSources(bool test_mode) {
   has_attempted_reload_ = true;
   reload_context_ = new IsolateReloadContext(this, test_mode);
   reload_context_->StartReload();
-  delete reload_context_;
-  reload_context_ = NULL;
 }
 #endif  // !PRODUCT
 
@@ -1117,6 +1115,8 @@ void Isolate::DoneFinalizing() {
       if (!reload_context_->has_error()) {
         reload_context_->ReportSuccess();
       }
+      delete reload_context_;
+      reload_context_ = NULL;
     }
   )
 }