Structured cloning: improve DataCloneError reporting.

Source/bindings/v8/ExceptionState.h

Index: Source/bindings/v8/ExceptionState.h
diff --git a/Source/bindings/v8/ExceptionState.h b/Source/bindings/v8/ExceptionState.h
index bfe2790e16a84ac1aa19d47d039b94074bdf9fe8..d86754138fc31c8261c5a095d4a5a558ea6e6420 100644
--- a/Source/bindings/v8/ExceptionState.h
+++ b/Source/bindings/v8/ExceptionState.h
@@ -106,6 +106,8 @@ public:
     const char* propertyName() const { return m_propertyName; }
     const char* interfaceName() const { return m_interfaceName; }
 
+    void setException(v8::Handle<v8::Value>);

[Mike West, 2013/12/13 21:22:59]

Why is this now public? I don't see where you need to use it outside
ExceptionState.

[sof, 2013/12/13 21:51:33]

It's used to transfer the exception from the TryCatch in
SerializedScriptValue::SerializedScriptValue() --

 https://codereview.chromium.org/114363002/patch/1/10024

It gave me pause to do so, but I thought it fairly reasonable to have a public
ExceptionState method for setting a pre-constructed exception value also.

[Dmitry Lomov (no reviews), 2013/12/16 09:14:39]

I think the naming of methods on ExceptionState is confusing. All
'throw*Exception' methods do not actually throw, they just set the state on
ExceptionState. The only method that actually throws is 'throwIfNeeded'. 
If we follow this, a bit confusing, state of the API, the good name for a public
'setException' would be 'rethrowV8Exception' (throwIfNeeded will just propagate
the exception).

In the long run, I suggest renaming all 'throw*Exception' => 'report*Exception'

+
 protected:
     ExceptionCode m_code;
     Context m_context;
@@ -113,8 +115,6 @@ protected:
     const char* m_interfaceName;
 
 private:
-    void setException(v8::Handle<v8::Value>);
-
     String addExceptionContext(const String&) const;
 
     ScopedPersistent<v8::Value> m_exception;