Crashy PHP node causes search index to fail, misreports condition as "Cron run exceeded the time limit and was aborted"

To reproduce:
- Create a PHP node with any fatal error
- Run cron

Expected / Desired behavior:
- Watchdog entry that a particular node is broken
- Search indexing continues beyond failed node

Actual behavior:
- Cron fails with "Cron run exceeded the time limit and was aborted"
- Search indexing never gets beyond failed node

Suggested remedy:
Suggest trapping errors in the _node_index_node() loop of node_update_index() and watchdogging errored node IDs -- perhaps by calling @_node_index_node() and checking $php_errormsg; tho not sure if this is a good idea / compliant with current practices (i'm not finding best practices / coding standards re: error handling).

This may be called a corner case, but I've found a fair amount of forum activity around this error. In the case of a major version upgrade, there is a likelihood of PHP nodes calling functions in modules that no longer exist, calling outdated functions, or otherwise broken PHP. On a heavily customized, content-heavy site there is no avenue for testing all current content for basic validity (other than search indexing!)

Here is an opportunity to help upgrading developers find invalid pages, rather than generate a confusing and inaccurate error message.

I've considered that this may be a search issue or a cron issue, but the real source is node_update_index().