DevTools: Don't show <exception> in Local scope of an async call frame.
DevTools: Don't show <exception> in Local scope of an async call frame.

We used to show current exception in the Local scope of all frames in the current stack.
Showing exception in the Local scope of an async stack frame is confusing.

R=pfeldman

Review URL: https://codereview.chromium.org/198253006

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@169337 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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