Editorial: have Create{,Async}IteratorFromClosure provide a new execu…

…tion context to GeneratorStart (#2398)

spec.html

@@ -39816,7 +39816,15 @@ <h1>CreateIteratorFromClosure ( _closure_, _generatorBrand_, _generatorPrototype
           1. Let _generator_ be ! OrdinaryObjectCreate(_generatorPrototype_, _internalSlotsList_).
           1. Set _generator_.[[GeneratorBrand]] to _generatorBrand_.
           1. Set _generator_.[[GeneratorState]] to *undefined*.
+          1. Let _callerContext_ be the running execution context.
+          1. Let _calleeContext_ be a new execution context.
+          1. Set the Function of _calleeContext_ to *null*.
+          1. Set the Realm of _calleeContext_ to the current Realm Record.
+          1. Set the ScriptOrModule of _calleeContext_ to _callerContext_'s ScriptOrModule.
+          1. If _callerContext_ is not already suspended, suspend _callerContext_.
+          1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
           1. Perform ! GeneratorStart(_generator_, _closure_).
+          1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
           1. Return _generator_.
         </emu-alg>
       </emu-clause>
@@ -40115,7 +40123,15 @@ <h1>CreateAsyncIteratorFromClosure ( _closure_, _generatorBrand_, _generatorProt
           1. Let _generator_ be ! OrdinaryObjectCreate(_generatorPrototype_, _internalSlotsList_).
           1. Set _generator_.[[GeneratorBrand]] to _generatorBrand_.
           1. Set _generator_.[[AsyncGeneratorState]] to *undefined*.
+          1. Let _callerContext_ be the running execution context.
+          1. Let _calleeContext_ be a new execution context.
+          1. Set the Function of _calleeContext_ to *null*.
+          1. Set the Realm of _calleeContext_ to the current Realm Record.
+          1. Set the ScriptOrModule of _calleeContext_ to _callerContext_'s ScriptOrModule.
+          1. If _callerContext_ is not already suspended, suspend _callerContext_.
+          1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
           1. Perform ! AsyncGeneratorStart(_generator_, _closure_).
+          1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
           1. Return _generator_.
         </emu-alg>
       </emu-clause>