BrowserUnitTests: get commit infos
report.html: display tests run time
Save and display total testing time
run_tests: If arg is an HASH ref, use it instead of tbb_filename_infos
Add a is_test_error subroutine
Replace fatal boolean with fail_type fatal value
Set default fail_type to 'error'
report.html: display fail_type
Make the is_test_error sub available to templates

And use it in report.html
Add static/warning.png

Public domain image downloaded from:
http://www.wpclipart.com/computer/icons/other_icons/exclamation_triangle_blue.png.html
Resize warning.png to warning-small.png
Remove trailing / from xpcshell dir
Add 'warning' fail_type
Rename failed_tests to error_tests
set_report_success: simplify
Display the list of test warnings
report.html: improve display of results