Dispatching errors across iframes don't match webplatform tests

third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp b/third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp
index fa788f05a87ee8719f83a883275ee539675bb84e..100c161c3e1bd9c574d738d5b4c35b324b64e70f 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8EventListener.cpp
@@ -102,11 +102,19 @@ v8::Local<v8::Value> V8EventListener::callListenerFunction(
 
   v8::Local<v8::Value> parameters[1] = {jsEvent};
   v8::Local<v8::Value> result;
+  ScriptState* scriptStateForFunction = ScriptState::from(handlerFunction->CreationContext());
+  if (scriptStateForFunction->getExecutionContext() != scriptState->getExecutionContext())
+    scriptState->getExecutionContext()->setErrorEventScriptState(scriptStateForFunction);

[dominicc (has gone to gerrit), 2016/10/16 08:45:57]

I think you should write a stack allocated object which sets this script state
in its constructor and clears it in its destructor. The call site will be simple
and more reliable--we won't need to track all the returns; we will be less
likely to have bugs where the error event script state isn't reset.

I think you should simply *always* set and reset the script state (or maybe it
should be the context instead, since that's lighter?)

In addition, you need to CHECK that the error event script state isn't set/is
set to the same context when setting this. Because you set and clear it, if
there's a nested event listener call it will be reset too early. Could you add a
test for something like this?

[Anton Obzhirov, 2016/10/17 09:49:34]

Yes, I was thinking about setting context as well. Good point about nested call,
will develop a test for that.

+
   if (!V8ScriptRunner::callFunction(handlerFunction, frame->document(),
                                     receiver, WTF_ARRAY_LENGTH(parameters),
                                     parameters, scriptState->isolate())
-           .ToLocal(&result))
+           .ToLocal(&result)) {
+    scriptState->getExecutionContext()->clearErrorEventScriptState();
     return v8::Local<v8::Value>();
+  }
+
+  scriptState->getExecutionContext()->clearErrorEventScriptState();
   return result;
 }