[snapshot] Move builtins generation into mksnapshot

src/api.cc

 // 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.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 8163 matching lines @@
 
 
 Isolate* Isolate::GetCurrent() {
   i::Isolate* isolate = i::Isolate::Current();
   return reinterpret_cast<Isolate*>(isolate);
 }
 
 
 Isolate* Isolate::New(const Isolate::CreateParams& params) {
   i::Isolate* isolate = new i::Isolate(false);
+  return IsolateNewImpl(isolate, params);
+}
+
+// This is separate so that tests can provide a different |isolate|.
+Isolate* IsolateNewImpl(internal::Isolate* isolate,
+                        const v8::Isolate::CreateParams& params) {
   Isolate* v8_isolate = reinterpret_cast<Isolate*>(isolate);
   CHECK(params.array_buffer_allocator != NULL);
   isolate->set_array_buffer_allocator(params.array_buffer_allocator);
   if (params.snapshot_blob != NULL) {
     isolate->set_snapshot_blob(params.snapshot_blob);
   } else {
     isolate->set_snapshot_blob(i::Snapshot::DefaultSnapshotBlob());
   }
   if (params.entry_hook) {
 #ifdef V8_USE_SNAPSHOT
@@ skipping 2115 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8