Revert "VM: [Kernel] elide parent context setup if it's empty"

runtime/vm/kernel_to_il.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <set>
 #include <string>
 
 #include "vm/kernel_to_il.h"
 
 #include "vm/compiler.h"
@@ skipping 2293 matching lines @@
     instructions += LoadContextAt(depth);
     instructions += StoreLocal(TokenPosition::kNoSource,
                                parsed_function_->current_context_var());
     instructions += Drop();
     context_depth_ = depth;
   }
   return instructions;
 }
 
 
-bool FlowGraphBuilder::HasContextScope() const {
-  const ContextScope& context_scope =
-      ContextScope::Handle(parsed_function_->function().context_scope());
-  return !context_scope.IsNull() && context_scope.num_variables() > 0;
-}
-
-
 Fragment FlowGraphBuilder::PushContext(int size) {
   ASSERT(size > 0);
   Fragment instructions = AllocateContext(size);
-  if (context_depth_ != 0 || HasContextScope()) {
-    LocalVariable* context = MakeTemporary();
-    instructions += LoadLocal(context);
-    instructions += LoadLocal(parsed_function_->current_context_var());
-    instructions +=
-        StoreInstanceField(TokenPosition::kNoSource, Context::parent_offset());
-  }
+  LocalVariable* context = MakeTemporary();
+  instructions += LoadLocal(context);
+  instructions += LoadLocal(parsed_function_->current_context_var());
+  instructions +=
+      StoreInstanceField(TokenPosition::kNoSource, Context::parent_offset());
   instructions += StoreLocal(TokenPosition::kNoSource,
                              parsed_function_->current_context_var());
   ++context_depth_;
   return instructions;
 }
 
 
 Fragment FlowGraphBuilder::PopContext() {
   return AdjustContextTo(context_depth_ - 1);
 }
@@ skipping 4491 matching lines @@
     thread->clear_sticky_error();
     return error.raw();
   }
 }
 
 
 }  // namespace kernel
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)