document.lastModified should consider user's local time zone

Source/core/testing/Internals.cpp

Index: Source/core/testing/Internals.cpp
diff --git a/Source/core/testing/Internals.cpp b/Source/core/testing/Internals.cpp
index 407ebf0fd68ee3b0a283d666061a8cb6dedd289c..f24dff96eb73c57c0a336793a7f3962cc8edfefa 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -134,6 +134,7 @@
 #include "public/platform/WebGraphicsContext3D.h"
 #include "public/platform/WebGraphicsContext3DProvider.h"
 #include "public/platform/WebLayer.h"
+#include "wtf/DateMath.h"
 #include "wtf/InstanceCounter.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/dtoa.h"
@@ -2341,4 +2342,9 @@ String Internals::serializeNavigationMarkup(Document* document)
     return markup.toString();
 }
 
+double Internals::convertToLocalTime(double ms)
+{
+    return WTF::convertToLocalTime(ms);
+}
+
 } // namespace blink