[serializer] include global proxy in additional context snapshots.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 6b9917f08a94bd1818be563faa75e4b05662f2a3..22b811d3f61d8b5cf227000d5aa4eebcc27e0331 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -907,12 +907,6 @@ class Isolate {
 
   Builtins* builtins() { return &builtins_; }
 
-  void NotifyExtensionInstalled() {
-    has_installed_extensions_ = true;
-  }
-
-  bool has_installed_extensions() { return has_installed_extensions_; }
-
   unibrow::Mapping<unibrow::Ecma262Canonicalize>*
       regexp_macro_assembler_canonicalize() {
     return &regexp_macro_assembler_canonicalize_;
@@ -1344,7 +1338,6 @@ class Isolate {
   ThreadManager* thread_manager_;
   RuntimeState runtime_state_;
   Builtins builtins_;
-  bool has_installed_extensions_;
   unibrow::Mapping<unibrow::Ecma262UnCanonicalize> jsregexp_uncanonicalize_;
   unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
   unibrow::Mapping<unibrow::Ecma262Canonicalize>