Color Management In Various Web Browsers For Untagged Images Broken Since 10.8 Upgrade

I have recently updated my early 2008 Mac Pro to 10.8 and have noticed that neither Safari, Firefox or Chrome handle untagged images correctly anymore. Instead of assuming sRGB as the ICC profile for an untagged image (like they did prior to upgrading), they now just convert to monitor profile which looks over-saturated on my wide gamut monitor (Dell 3007WFPHC, hardware calibrated with a Datacolor Spyder 3 Pro). Color management in Photoshop, Lightroom and all other previosuly color-aware applications appears unaltered. The interesting thing is that in Safari, if I open a link with "open in new tab", the untagged images are rendered as if their color profiles are sRGB and are displayed correctly! But just clicking the link in the same tab or "open in new window" results in the incorrect over-saturated colors. This doesn't make any sense. Anyone else have this same issue?