Remove the patching of the debug break stub...

src/debug.cc

Index: src/debug.cc
===================================================================
--- src/debug.cc	(revision 5725)
+++ src/debug.cc	(working copy)
@@ -1464,8 +1464,7 @@
 // location.
 bool Debug::IsBreakStub(Code* code) {
   CodeStub::Major major_key = CodeStub::GetMajorKey(code);
-  return major_key == CodeStub::CallFunction ||
-         major_key == CodeStub::StackCheck;
+  return major_key == CodeStub::CallFunction;
 }
 
 
@@ -1503,8 +1502,7 @@
     return result;
   }
   if (code->kind() == Code::STUB) {
-    ASSERT(code->major_key() == CodeStub::CallFunction ||
-           code->major_key() == CodeStub::StackCheck);
+    ASSERT(code->major_key() == CodeStub::CallFunction);
     Handle<Code> result =
         Handle<Code>(Builtins::builtin(Builtins::StubNoRegisters_DebugBreak));
     return result;