This function would be used for performance testing metric collection. The Chrome browser currently shows the heap contents if you take a snapshot. But we have no programmatic access to that type of data. Adding a JavaScript function (along with getProfile() https://bugs.webkit.org/show_bug.cgi?id=31133) would give an html page all the tools necessary to collect performance data, and manipulate/collate that data. My personal interest is in building pages that collect data and report that data back to a server for collation/reporting. Currently the interesting 3 core interesting metrics are time, count, and memory usage. we have basic timing, but we don't have a way to characterize memory usage. This function with getProfile() would complete the circle. Now the information is data, and can be collected and collated with other data from other places. I will be adding a bug at Firebug requesting to add a function like this there also.
I think this has been superseded by the Navigation Timing API (aka Web Timing API). http://test.w3.org/webperf/specs/NavigationTiming/ http://www.html5rocks.com/en/tutorials/webperformance/basics/ http://webtimingdemo.appspot.com/
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests. Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.