Use auto-rethrowing v8::TryCatch variant

Source/bindings/v8/V8Binding.h

 /*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2012 Ericsson AB. 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.
@@ skipping 922 matching lines @@
 
 private:
     v8::HandleScope m_handleScope;
     v8::Context::Scope m_contextScope;
     RefPtr<ScriptState> m_scriptState;
 };
 
 void GetDevToolsFunctionInfo(v8::Handle<v8::Function>, v8::Isolate*, int& scriptId, String& resourceName, int& lineNumber);
 PassRefPtr<TraceEvent::ConvertableToTraceFormat> devToolsTraceEventData(ExecutionContext*, v8::Handle<v8::Function>, v8::Isolate*);
 
+class V8RethrowTryCatchScope FINAL {
+public:
+    explicit V8RethrowTryCatchScope(v8::TryCatch& block) : m_block(block) { }
+    ~V8RethrowTryCatchScope()
+    {
+        // ReThrow() is a no-op if no exception has been caught, so always call.
+        m_block.ReThrow();
+    }
+
+private:
+    v8::TryCatch& m_block;
+};
+
+class V8ResetTryCatchScope FINAL {
+public:
+    explicit V8ResetTryCatchScope(v8::TryCatch& block) : m_block(block) { }
+    ~V8ResetTryCatchScope()
+    {
+        m_block.Reset();
+    }
+
+private:
+    v8::TryCatch& m_block;
+};
 
 } // namespace WebCore
 
 #endif // V8Binding_h