Fix grokdump inspector search for invalid addresses.

R=ulan@chromium.org
TEST=tools/grokdump.py

Review URL: https://chromiumcodereview.appspot.com/10467003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11701 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/grokdump.py

@@ -1462,6 +1462,9 @@ class InspectionShell(cmd.Cmd):
     for slot in xrange(start,
                        start + self.reader.PointerSize() * 10,
                        self.reader.PointerSize()):
+      if not self.reader.IsValidAddress(slot):
+        print "Address is not contained within the minidump!"
+        return
       maybe_address = self.reader.ReadUIntPtr(slot)
       heap_object = self.padawan.SenseObject(maybe_address)
       print "%s: %s %s" % (self.reader.FormatIntPtr(slot),