Fix ExceptionState with empty context.

Source/bindings/v8/ExceptionState.cpp

Index: Source/bindings/v8/ExceptionState.cpp
diff --git a/Source/bindings/v8/ExceptionState.cpp b/Source/bindings/v8/ExceptionState.cpp
index 1d95598c623298e3a1156d06502bf2ba0e973d37..d51325cc41d93c62dd52267f61879a44b7235e9f 100644
--- a/Source/bindings/v8/ExceptionState.cpp
+++ b/Source/bindings/v8/ExceptionState.cpp
@@ -47,6 +47,7 @@ void ExceptionState::throwDOMException(const ExceptionCode& ec, const String& me
 {
     ASSERT(ec);
     ASSERT(m_isolate);
+    ASSERT(!m_creationContext.IsEmpty());
 
     // SecurityError is thrown via ::throwSecurityError, and _careful_ consideration must be given to the data exposed to JavaScript via the 'sanitizedMessage'.
     ASSERT(ec != SecurityError);
@@ -60,6 +61,7 @@ void ExceptionState::throwDOMException(const ExceptionCode& ec, const String& me
 void ExceptionState::throwSecurityError(const String& sanitizedMessage, const String& unsanitizedMessage)
 {
     ASSERT(m_isolate);
+    ASSERT(!m_creationContext.IsEmpty());
     m_code = SecurityError;
     String finalSanitized = addExceptionContext(sanitizedMessage);
     m_message = finalSanitized;