This makes sure exception reporting done by the debug shell behaves
gracefully even near the stack limit. When line number determination
fails we just fallback to not printing source information.
R=yangguo@chromium.org
TEST=mjsunit/regress/regress-crbug-620253
BUG=chromium:620253
Review-Url: https://codereview.chromium.org/2069543007
Cr-Commit-Position: refs/heads/master@{#37031}
