Various clean-ups after top-level lexical declarations are done.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 5d001f46908e736b47ccd4df0ac66a65ae30618e..3cc46a02b060d19d33679ea319d1eccae561f803 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -821,9 +821,8 @@ class Isolate {
   void IterateThread(ThreadVisitor* v, char* t);
 
 
-  // Returns the current native and global context.
+  // Returns the current native context.
   Handle<Context> native_context();
-  Handle<Context> global_context();
 
   // Returns the native context of the calling JavaScript code.  That
   // is, the native context of the top-most JavaScript frame.