Implement Instance instances correctly; fix a few error cases

src/bootstrapper.cc

 // Copyright 2014 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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 4145 matching lines @@
 }
 
 
 bool Genesis::InstallSpecialObjects(Handle<Context> native_context) {
   Isolate* isolate = native_context->GetIsolate();
   // Don't install extensions into the snapshot.
   if (isolate->serializer_enabled()) return true;
 
   Factory* factory = isolate->factory();
   HandleScope scope(isolate);
-  Handle<JSGlobalObject> global(JSGlobalObject::cast(
-      native_context->global_object()));
 
   Handle<JSObject> Error = isolate->error_function();
   Handle<String> name =
       factory->InternalizeOneByteString(STATIC_CHAR_VECTOR("stackTraceLimit"));
   Handle<Smi> stack_trace_limit(Smi::FromInt(FLAG_stack_trace_limit), isolate);
   JSObject::AddProperty(Error, name, stack_trace_limit, NONE);
 
-  WasmJs::Install(isolate, global);
+  if (FLAG_expose_wasm || FLAG_validate_asm) {
+    WasmJs::Install(isolate);
+  }
 
   return true;
 }
 
 
 static uint32_t Hash(RegisteredExtension* extension) {
   return v8::internal::ComputePointerHash(extension);
 }
 
 Genesis::ExtensionStates::ExtensionStates() : map_(8) {}
@@ skipping 571 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8