Rethrow cross-site exceptions as security errors

Source/bindings/core/v8/V8DOMWrapper.h

Index: Source/bindings/core/v8/V8DOMWrapper.h
diff --git a/Source/bindings/core/v8/V8DOMWrapper.h b/Source/bindings/core/v8/V8DOMWrapper.h
index 4effd0697a064eca0ee39364987b9d0f0c84f47a..169979317b4e3a67f5f7122b71bb5fb2cc6009de 100644
--- a/Source/bindings/core/v8/V8DOMWrapper.h
+++ b/Source/bindings/core/v8/V8DOMWrapper.h
@@ -113,18 +113,24 @@ public:
     V8WrapperInstantiationScope(v8::Local<v8::Object> creationContext, v8::Isolate* isolate, bool withSecurityCheck = true)
         : m_didEnterContext(false)
         , m_context(isolate->GetCurrentContext())
+        , m_tryCatch(isolate)
+        , m_convertExceptions(false)
     {
         // creationContext should not be empty. Because if we have an
         // empty creationContext, we will end up creating
         // a new object in the context currently entered. This is wrong.
         RELEASE_ASSERT(!creationContext.IsEmpty());
         v8::Local<v8::Context> contextForWrapper = creationContext->CreationContext();
+
         // For performance, we enter the context only if the currently running context
         // is different from the context that we are about to enter.
         if (contextForWrapper == m_context)
             return;
-        if (withSecurityCheck)
+        if (withSecurityCheck) {
             securityCheck(isolate, contextForWrapper);
+        } else {
+            m_convertExceptions = true;
+        }
         m_context = v8::Local<v8::Context>::New(isolate, contextForWrapper);
         m_didEnterContext = true;
         m_context->Enter();
@@ -132,18 +138,31 @@ public:
 
     ~V8WrapperInstantiationScope()
     {
-        if (!m_didEnterContext)
+        if (!m_didEnterContext) {
+            m_tryCatch.ReThrow();
             return;
+        }
         m_context->Exit();
+        // Rethrow any cross-context exceptions as security error.
+        if (m_tryCatch.HasCaught()) {
+            if (m_convertExceptions) {
+                m_tryCatch.Reset();
+                convertException();
+            }
+            m_tryCatch.ReThrow();
+        }
     }
 
     v8::Local<v8::Context> context() const { return m_context; }
 
 private:
     void securityCheck(v8::Isolate*, v8::Local<v8::Context> contextForWrapper);
+    void convertException();
 
     bool m_didEnterContext;
     v8::Local<v8::Context> m_context;
+    v8::TryCatch m_tryCatch;
+    bool m_convertExceptions;
 };
 
 } // namespace blink