Fix PendingScript::errorOccurred() to be consistent with getSource()

Previously, PendingScript::errorOccurred() didn't take |m_integrityFailure|
into consideration while getSource()'s |errorOccurred| did.

This CL merges these two implementations and thus makes
PendingScript::errorOccurred() to take |m_integrityFailure| into consideration.

BUG=686281

Review-Url: https://codereview.chromium.org/2716543002
Cr-Commit-Position: refs/heads/master@{#452518}
1 file changed