Insurance — Commercial general liability — Duty to defend — Trial court improperly relied on extrinsic evidence in entering summary judgment finding that insurer had no duty to defend action against insured which installed failed fire suppressant system in aircraft hangar — Where insurer claimed that it did not have a duty to defend or indemnify because coverage was barred by policy’s total pollution exclusion, it was error for trial court, in granting summary judgment for insurer, to rely on insurer’s claims specialist’s Material Safety Data Sheet to determine that fire suppressant foam from system was a pollutant and excluded from coverage — Exception to general rule that insurer’s duty to defend is determined by allegations of complaint where claim that there is no duty to defend is based on factual issues that would not normally be alleged in complaint is inapplicable where extrinsic evidence was not uncontroverted or manifestly obvious so as to preclude coverage