IDL: make optional arguments (without default) explicit sometimes

Source/core/fileapi/Blob.h

Index: Source/core/fileapi/Blob.h
diff --git a/Source/core/fileapi/Blob.h b/Source/core/fileapi/Blob.h
index d1263177b5548e67aad7673675f9fadc0002af82..effe9464f5c947f725c67351bdc3c9a396f2724d 100644
--- a/Source/core/fileapi/Blob.h
+++ b/Source/core/fileapi/Blob.h
@@ -31,6 +31,7 @@
 #ifndef Blob_h
 #define Blob_h
 
+#include "bindings/core/v8/Optional.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/html/URLRegistry.h"
 #include "platform/blob/BlobData.h"
@@ -60,21 +61,7 @@ public:
     virtual ~Blob();
 
     virtual unsigned long long size() const { return m_blobDataHandle->size(); }
-    virtual PassRefPtrWillBeRawPtr<Blob> slice(long long start, long long end, const String& contentType, ExceptionState&) const;
-
-    // To allow ExceptionState to be passed in last, manually enumerate the optional argument overloads.
-    PassRefPtrWillBeRawPtr<Blob> slice(ExceptionState& exceptionState) const
-    {
-        return slice(0, std::numeric_limits<long long>::max(), String(), exceptionState);
-    }
-    PassRefPtrWillBeRawPtr<Blob> slice(long long start, ExceptionState& exceptionState) const
-    {
-        return slice(start, std::numeric_limits<long long>::max(), String(), exceptionState);
-    }
-    PassRefPtrWillBeRawPtr<Blob> slice(long long start, long long end, ExceptionState& exceptionState) const
-    {
-        return slice(start, end, String(), exceptionState);
-    }
+    virtual PassRefPtrWillBeRawPtr<Blob> slice(long long start, Optional<long long> optionalEnd, const String& contentType, ExceptionState&) const;
 
     virtual void close(ExecutionContext*, ExceptionState&);