Implement File constructor.

Source/core/fileapi/Blob.cpp

 /*
  * Copyright (C) 2010 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 64 matching lines @@
 Blob::~Blob()
 {
 }
 
 PassRefPtr<Blob> Blob::slice(long long start, long long end, const String& contentType) const
 {
     // When we slice a file for the first time, we obtain a snapshot of the file by capturing its current size and modification time.
     // The modification time will be used to verify if the file has been changed or not, when the underlying data are accessed.
     long long size;
     double modificationTime;
-    if (isFile()) {
+    if (hasBackingFile()) {
         // FIXME: This involves synchronous file operation. We need to figure out how to make it asynchronous.
         toFile(this)->captureSnapshot(size, modificationTime);
     } else {
         size = this->size();
         ASSERT(size != -1);
     }
 
     // Convert the negative value that is used to select from the end.
     if (start < 0)
         start = start + size;
     if (end < 0)
         end = end + size;
 
     // Clamp the range if it exceeds the size limit.
     if (start < 0)
         start = 0;
     if (end < 0)
         end = 0;
     if (start >= size) {
         start = 0;
         end = 0;
     } else if (end < start)
         end = start;
     else if (end > size)
         end = size;
 
     long long length = end - start;
     OwnPtr<BlobData> blobData = BlobData::create();
     blobData->setContentType(contentType);
-    if (isFile()) {
+    if (hasBackingFile()) {
         if (!toFile(this)->fileSystemURL().isEmpty())
             blobData->appendFileSystemURL(toFile(this)->fileSystemURL(), start, length, modificationTime);
         else
             blobData->appendFile(toFile(this)->path(), start, length, modificationTime);
     } else {
         blobData->appendBlob(m_blobDataHandle, start, length);
     }
     return Blob::create(BlobDataHandle::create(blobData.release(), length));
 }
 
 URLRegistry& Blob::registry() const
 {
     return BlobURLRegistry::registry();
 }
 
 
 } // namespace WebCore