Refactored the mirror representation of properties. Removed the AssessorMirror and InterceptorPropertyMirror and moved all reflection for properties to PropertyMirror. From a PropertyMirror it can be checked whether a property has getter/setter defined in JavaScript and information on the getter/setter functions are now available. If calling the getter resulted in an exception this is reflected as well.

Properties from interceptors are also reflected through PropertyMirror as the distinction did not make sense seen from a JavaScript debugging perspective. The isNative function on a PropertyMirror can be used to check whether a property is defined natively by the host (or V8).

Simplified the local property lookup in the debug runtime call to just call GetProperty as the property is known to be a local property.
Review URL: http://codereview.chromium.org/17377

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1068 ce2b1a6d-e550-0410-aec6-3dcde31c8c00