Bug 217308

#Version：
d940b47

#Testcase:
var f = function (){
    var x = 42; 
    new x(x = function (){});
}; 
f();

#Command:
./webkit/WebKitBuild/Release/bin/jsc testcase.js

#Output:

#Expected output:
TypeError: x is not a constructor

#Description:
When executing the above testcase, other engines threw a TypeError exception, such as v8, spiderMonkey, etc. But JavaScriptCore passed normally without throwing any exceptions.