File constructor understands lastModified.

Source/bindings/v8/custom/V8FileCustom.cpp

Index: Source/bindings/v8/custom/V8FileCustom.cpp
diff --git a/Source/bindings/v8/custom/V8FileCustom.cpp b/Source/bindings/v8/custom/V8FileCustom.cpp
index 6983ef2188946414cbbeb6a688c5b9914d1d3b51..81e12787b76efa4523ec697230d39fca59237262 100644
--- a/Source/bindings/v8/custom/V8FileCustom.cpp
+++ b/Source/bindings/v8/custom/V8FileCustom.cpp
@@ -62,24 +62,23 @@ void V8File::constructorCustom(const v8::FunctionCallbackInfo<v8::Value>& info)
 
     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 (!V8BlobCustomHelpers::processBlobPropertyBag(info[2], "File", properties, info.GetIsolate()))
             return;
     }
 
     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());
 }