Remove more dead code after Object.observe removal

src/isolate.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <queue>
 #include <set>
 
@@ skipping 607 matching lines @@
   }
   inline Address* js_entry_sp_address() {
     return &thread_local_top_.js_entry_sp_;
   }
 
   // Returns the global object of the current context. It could be
   // a builtin object, or a JS global object.
   inline Handle<JSGlobalObject> global_object();
 
   // Returns the global proxy object of the current context.
-  JSObject* global_proxy() {
-    return context()->global_proxy();
-  }
+  inline Handle<JSObject> global_proxy();
 
   static int ArchiveSpacePerThread() { return sizeof(ThreadLocalTop); }
   void FreeThreadResources() { thread_local_top_.Free(); }
 
   // This method is called by the api after operations that may throw
   // exceptions.  If an exception was thrown and not handled by an external
   // handler the exception is scheduled to be rethrown when we return to running
   // JavaScript code.  If an exception is scheduled true is returned.
   bool OptionalRescheduleException(bool is_bottom_call);
 
@@ skipping 941 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_