Add asserts and state tracking to ensure that we do not call

src/x64/code-stubs-x64.h

Index: src/x64/code-stubs-x64.h
===================================================================
--- src/x64/code-stubs-x64.h	(revision 8110)
+++ src/x64/code-stubs-x64.h	(working copy)
@@ -65,6 +65,8 @@
 
   void Generate(MacroAssembler* masm);
 
+  virtual bool SometimesSetsUpAFrame() { return false; }
+
  private:
   Major MajorKey() { return ToBoolean; }
   int MinorKey() { return 0; }
@@ -469,6 +471,8 @@
                                      Register r0,
                                      Register r1);
 
+  virtual bool SometimesSetsUpAFrame() { return false; }
+
  private:
   static const int kInlinedProbes = 4;
   static const int kTotalProbes = 20;
@@ -488,7 +492,7 @@
   }
 #endif
 
-  Major MajorKey() { return StringDictionaryNegativeLookup; }
+  Major MajorKey() { return StringDictionaryLookup; }
 
   int MinorKey() {
     return DictionaryBits::encode(dictionary_.code()) |