Fix a leak with g_DefaultGlobalObjectTemplate.

As seen when running FXJSV8Embeddertest.Getters.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1380993003 .
diff --git a/fpdfsdk/src/jsapi/fxjs_v8.cpp b/fpdfsdk/src/jsapi/fxjs_v8.cpp
index 54044e2..70cdc2d 100644
--- a/fpdfsdk/src/jsapi/fxjs_v8.cpp
+++ b/fpdfsdk/src/jsapi/fxjs_v8.cpp
@@ -145,6 +145,7 @@
 
 void FXJS_Release() {
   ASSERT(!g_isolate || g_isolate_ref_count == 0);
+  delete g_DefaultGlobalObjectTemplate;
   g_DefaultGlobalObjectTemplate = nullptr;
   g_isolate = nullptr;