DevTools: Fix Crash Report - v8::Value::IsInt32.
DevTools: Fix Crash Report - v8::Value::IsInt32.

BUG=397440
R=yurys

Review URL: https://codereview.chromium.org/416363002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@179116 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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