Decouple root visitors from object visitors.

src/bootstrapper.h

Index: src/bootstrapper.h
diff --git a/src/bootstrapper.h b/src/bootstrapper.h
index 059d3725735a711b42110015885e1d4329690b5d..286ec1ad54175cc8a9ef67ca1b6ea3527a26a235 100644
--- a/src/bootstrapper.h
+++ b/src/bootstrapper.h
@@ -7,6 +7,7 @@
 
 #include "src/factory.h"
 #include "src/snapshot/natives.h"
+#include "src/visitors.h"
 
 namespace v8 {
 namespace internal {
@@ -24,8 +25,9 @@ class SourceCodeCache final BASE_EMBEDDED {
     cache_ = create_heap_objects ? isolate->heap()->empty_fixed_array() : NULL;
   }
 
-  void Iterate(ObjectVisitor* v) {
-    v->VisitPointer(bit_cast<Object**, FixedArray**>(&cache_));
+  void Iterate(RootVisitor* v) {
+    v->VisitRootPointer(Root::kExtensions,
+                        bit_cast<Object**, FixedArray**>(&cache_));
   }
 
   bool Lookup(Vector<const char> name, Handle<SharedFunctionInfo>* handle) {
@@ -94,7 +96,7 @@ class Bootstrapper final {
   void DetachGlobal(Handle<Context> env);
 
   // Traverses the pointers for memory management.
-  void Iterate(ObjectVisitor* v);
+  void Iterate(RootVisitor* v);
 
   // Accessor for the native scripts source code.
   Handle<String> GetNativeSource(NativeType type, int index);