Inflict PDF_ENABLE_XFA ifdefs on XFA fpdfsdk/

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1477583002 .
diff --git a/fpdfsdk/src/javascript/JS_Context.cpp b/fpdfsdk/src/javascript/JS_Context.cpp
index 76988d5..e59b1a7 100644
--- a/fpdfsdk/src/javascript/JS_Context.cpp
+++ b/fpdfsdk/src/javascript/JS_Context.cpp
@@ -35,7 +35,9 @@
 FX_BOOL CJS_Context::RunScript(const CFX_WideString& script,
                                CFX_WideString* info) {
   v8::Isolate::Scope isolate_scope(m_pRuntime->GetIsolate());
+#ifdef PDF_ENABLE_XFA
   v8::Locker locker(m_pRuntime->GetIsolate());
+#endif
   v8::HandleScope handle_scope(m_pRuntime->GetIsolate());
   v8::Local<v8::Context> context = m_pRuntime->NewJSContext();
   v8::Context::Scope context_scope(context);