Fix JS seconds since epoch to date conversions.

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_config") {
   cflags = []
@@ skipping 757 matching lines @@
     "testing/embedder_test_timer_handling_delegate.h",
   ]
   deps = [
     "//testing/gmock",
     "//testing/gtest",
     ":pdfium",
     ":test_support",
   ]
   include_dirs = []
   if (pdf_enable_v8) {
-    sources += [ "fpdfsdk/src/jsapi/fxjs_v8_embeddertest.cpp" ]
+    sources += [
+      "fpdfsdk/src/javascript/public_methods_embeddertest.cpp",
+      "fpdfsdk/src/jsapi/fxjs_v8_embeddertest.cpp",
+      "testing/js_embedder_test.cpp",
+      "testing/js_embedder_test.h",
+    ]
     deps += [
       "//v8",
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }