Revert of [snapshot] Move builtins generation into mksnapshot

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 7b114d088b3e91c978ca7d04608156c735ed1764..29d63ce047af6136605ba62118069f96f2996096 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -26,8 +26,6 @@
 #include "src/runtime/runtime.h"
 #include "src/zone/zone.h"
 
-class TestIsolate;
-
 namespace v8 {
 
 namespace base {
@@ -80,7 +78,6 @@ class OptimizingCompileDispatcher;
 class RegExpStack;
 class RuntimeProfiler;
 class SaveContext;
-class SetupIsolateDelegate;
 class StatsTable;
 class StringTracker;
 class StubCache;
@@ -1434,7 +1431,6 @@ class Isolate {
   ThreadManager* thread_manager_;
   RuntimeState runtime_state_;
   Builtins builtins_;
-  SetupIsolateDelegate* setup_delegate_;
   unibrow::Mapping<unibrow::Ecma262UnCanonicalize> jsregexp_uncanonicalize_;
   unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
   unibrow::Mapping<unibrow::Ecma262Canonicalize>
@@ -1575,7 +1571,6 @@ class Isolate {
   friend class v8::Locker;
   friend class v8::Unlocker;
   friend class v8::SnapshotCreator;
-  friend class ::TestIsolate;
   friend v8::StartupData v8::V8::CreateSnapshotDataBlob(const char*);
   friend v8::StartupData v8::V8::WarmUpSnapshotDataBlob(v8::StartupData,
                                                         const char*);