When calling the throw method on a generator suspended inside a yield*, yield*
in turn tries to call throw on its iterable. If the iterable does not provide a
throw method, yield* must try to call the return method instead and then throw a
TypeError. Due to a bug in our desugaring, we never threw the TypeError.
R=adamk@chromium.org
BUG=v8:5132
Review-Url: https://codereview.chromium.org/2094253002
Cr-Commit-Position: refs/heads/master@{#37314}
2f0cb3afa3