Merge to XFA: Fix JS seconds since epoch to date conversions.

BUG=515137,564736
TBR=ochang@chromium.org, tsepez@chromium.org

Review URL: https://codereview.chromium.org/1533233002 .
Review URL: https://codereview.chromium.org/1544493003 .

(cherry picked from commit b426e3edde040089b70d1a223c83b90957aa571d)
(cherry picked from commit bd35d484a4027775f19ff93e9143e0b270133d42)

Review URL: https://codereview.chromium.org/1546443002 .
diff --git a/testing/js_embedder_test.h b/testing/js_embedder_test.h
new file mode 100644
index 0000000..167aea7
--- /dev/null
+++ b/testing/js_embedder_test.h
@@ -0,0 +1,32 @@
+// Copyright 2015 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef TESTING_JS_EMBEDDER_TEST_H_
+#define TESTING_JS_EMBEDDER_TEST_H_
+
+#include <vector>
+
+#include "fpdfsdk/include/jsapi/fxjs_v8.h"
+#include "testing/embedder_test.h"
+#include "third_party/base/nonstd_unique_ptr.h"
+
+class JSEmbedderTest : public EmbedderTest {
+ public:
+  JSEmbedderTest();
+  ~JSEmbedderTest() override;
+
+  void SetUp() override;
+  void TearDown() override;
+
+  v8::Isolate* isolate();
+  v8::Local<v8::Context> GetV8Context();
+
+ private:
+  nonstd::unique_ptr<FXJS_ArrayBufferAllocator> m_pArrayBufferAllocator;
+  v8::Isolate* m_pIsolate;
+  v8::Global<v8::Context> m_pPersistentContext;
+  std::vector<v8::Global<v8::Object>*> m_StaticObjects;
+};
+
+#endif  // TESTING_JS_EMBEDDER_TEST_H_