[deoptimizer] When deoptimizing code, unlink all functions referring to that code.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index 8994147ae06e2566006c7e121c6818faff99967d..3c1516c5ab0e00843b018b98ac92ea0eac3499d5 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -1413,9 +1413,6 @@ class EnumerateOptimizedFunctionsVisitor: public OptimizedFunctionVisitor {
                                      int* count)
       : sfis_(sfis), code_objects_(code_objects), count_(count) {}
 
-  virtual void EnterContext(Context* context) {}
-  virtual void LeaveContext(Context* context) {}
-
   virtual void VisitFunction(JSFunction* function) {
     SharedFunctionInfo* sfi = SharedFunctionInfo::cast(function->shared());
     Object* maybe_script = sfi->script();