This happens on Qt and Mac as well. I haven't run interpreter for ages, especially not in debug mode. Now, I got the following assertion fail: ASSERTION FAILED: protoObject->get(callFrame, callFrame->codeBlock()->identifier(vPC[3].u.operand)) == protoObject->getDirectOffset(offset) JavaScriptCore/interpreter/Interpreter.cpp:2143 Mext week I am going to abroad, and I don't have time to debug it now. But I open a bug report to not forget it.
See also: bug 31871.
I don't see any assertion failures when opening maps.google.com with r58015 on PowerPC.
Hm I forgot about this bug. Very old. Probably already fixed.