File constructor understands lastModified.

Source/bindings/v8/custom/V8FileCustom.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 44 matching lines @@
     } else {
         const int sequenceArgumentIndex = 0;
         if (toV8Sequence(info[sequenceArgumentIndex], length, info.GetIsolate()).IsEmpty()) {
             throwTypeError(ExceptionMessages::failedToConstruct("File", ExceptionMessages::notAnArrayTypeArgumentOrValue(sequenceArgumentIndex + 1)), info.GetIsolate());
             return;
         }
     }
 
     V8TRYCATCH_FOR_V8STRINGRESOURCE_VOID(V8StringResource<>, fileName, info[1]);
 
-    String contentType;
-    String endings = "transparent"; // default if no BlobPropertyBag is passed
+    V8BlobCustomHelpers::ParsedProperties properties(true);
     if (info.Length() > 2) {
         if (!info[2]->IsObject()) {
             throwTypeError(ExceptionMessages::failedToConstruct("File", "The 3rd argument is not of type Object."), info.GetIsolate());
             return;
         }
 
-        if (!V8BlobCustomHelpers::processBlobPropertyBag(info[2], "File", contentType, endings, info.GetIsolate()))
+        if (!properties.parseBlobPropertyBag(info[2], "File", info.GetIsolate()))
             return;
+    } else {
+        properties.setDefaultLastModifiedDate();
     }
 
     BlobBuilder blobBuilder;
     v8::Local<v8::Object> blobParts = v8::Local<v8::Object>::Cast(info[0]);
-    if (!V8BlobCustomHelpers::processBlobParts(blobParts, length, endings, blobBuilder, info.GetIsolate()))
+    if (!V8BlobCustomHelpers::processBlobParts(blobParts, length, properties.endings, blobBuilder, info.GetIsolate()))
         return;
 
-    RefPtr<File> file = blobBuilder.createFile(contentType, fileName, currentTime());
+    RefPtr<File> file = blobBuilder.createFile(properties.contentType, fileName, properties.lastModifiedDate());
     v8SetReturnValue(info, file.release());
 }
 
+void V8File::lastModifiedDateAttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>& info)
+{
+    // The auto-generated getters return null when the method in the underlying
+    // implementation returns NaN. Here, we need to return a Date whose value
+    // is NaN when the File constructor receives such a Date. WebIDL calls it
+    // an "undefined date". Fortunately, lastModifiedDate never needs to return
+    // null, so we can get away with mapping NaN to "new Date(NaN)" instead of
+    // "null".
+    //
+    // See step 3.3 in Section 7.1, and Section 7.2 of the File API spec:
+    // http://dev.w3.org/2006/webapi/FileAPI/
+    //
+    // See the following sections of the WebIDL ED:
+    // 3.10.26: http://heycam.github.io/webidl/#idl-Date
+    // 4.2.27: http://heycam.github.io/webidl/#es-Date
+
+    File* file = V8File::toNative(info.Holder());
+    v8SetReturnValue(info, v8::Date::New(file->lastModifiedDate()));

[kinuko, 2013/11/18 14:16:59]

(Going back to this one) so for NaN case should we return Date.now() given that
we use NaN for invalid case and if we basically try to follow the File API?

[pwnall-personal, 2013/11/18 14:44:35]

Thank you for pointing this out again! I think I just realized the full extent
of what you're trying to say. Sorry for being slow!

If NaN means "return Date.now()", then we need to figure out how to handle the
case "lastModifiedDate: new Date(NaN)".

Right now, I think the most reasonable thing to do is to consider that Step 3.3
in Section 7.1 of the File API excludes invalid dates. Specifically, I would
interpret it as:
"If the lastModifiedDate member is provided, and it is not the invalid Date, let
d be set to the lastModifiedDate dictionary member."

In this case, I'd set lastModifiedDate to the time when the File object is
constructed. Does this seem reasonable?

+}
+
 } // namespace WebCore