Implement Blob.close().

Source/core/fileapi/File.cpp

Index: Source/core/fileapi/File.cpp
diff --git a/Source/core/fileapi/File.cpp b/Source/core/fileapi/File.cpp
index de776d5acfee62729976119c903e6f667c9a3112..ad3ad935b862be53b72d657fa18865ded433fef0 100644
--- a/Source/core/fileapi/File.cpp
+++ b/Source/core/fileapi/File.cpp
@@ -225,6 +225,17 @@ void File::captureSnapshot(long long& snapshotSize, double& snapshotModification
     snapshotModificationTime = metadata.modificationTime;
 }
 
+void File::close(ExecutionContext* executionContext)
+{
+    if (!hasBeenClosed()) {
+        m_hasBackingFile = false;
+        m_relativePath = String();
+        m_path = String();

[kinuko, 2014/02/12 12:52:00]

There're more fields in this class (e.g. m_name)-- should we also clear them?

[sof, 2014/02/12 12:53:46]

The name of the Blob isn't currently spec'ed as going away when closed.

[kinuko, 2014/02/12 13:26:25]

I see thanks. Could we clear m_fileSystemURL too then as it could be internally
used in a similar way as m_path?  (Also having a short comment about why we
don't clear m_name here might help avoiding similar questions)

[sof, 2014/02/12 22:28:26]

Yes, better do both.

[sof, 2014/02/13 09:59:57]

Done now.

+        invalidateSnapshotMetadata();
+        Blob::close(executionContext);
+    }
+}
+
 void File::appendTo(BlobData& blobData) const
 {
     if (!m_hasBackingFile) {