Be less aggressive in sharing contexts between scopes so that sibling contexts

runtime/vm/object_test.cc

 // Copyright (c) 2012, 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 "platform/globals.h"
 
 #include "vm/assembler.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 2455 matching lines @@
   test_only = false;  // Please, insert alias.
   var_c = local_scope->LookupVariable(c, test_only);
   EXPECT(var_c->is_captured());
 
   EXPECT_EQ(3, local_scope->num_variables());  // a, b, and c alias.
   EXPECT_EQ(2, local_scope->NumCapturedVariables());  // a, c alias.
 
   const int first_parameter_index = 0;
   const int num_parameters = 0;
   const int first_frame_index = -1;
-  LocalScope* loop_owner = parent_scope;
-  LocalScope* context_owner = NULL;   // No context allocated yet.
   bool found_captured_vars = false;
   int next_frame_index = parent_scope->AllocateVariables(first_parameter_index,
                                                          num_parameters,
                                                          first_frame_index,
-                                                         loop_owner,
-                                                         &context_owner,
+                                                         NULL,
                                                          &found_captured_vars);
   EXPECT_EQ(first_frame_index, next_frame_index);  // a and c not in frame.
-  EXPECT_EQ(parent_scope, context_owner);  // parent_scope allocated a context.
   const intptr_t parent_scope_context_level = 1;
   EXPECT_EQ(parent_scope_context_level, parent_scope->context_level());
   EXPECT(found_captured_vars);
 
   const intptr_t local_scope_context_level = 5;
   const ContextScope& context_scope = ContextScope::Handle(
       local_scope->PreserveOuterScope(local_scope_context_level));
   LocalScope* outer_scope = LocalScope::RestoreOuterScope(context_scope);
   EXPECT_EQ(2, outer_scope->num_variables());
 
@@ skipping 1981 matching lines @@
   EXPECT_VALID(h_result);
   Integer& result = Integer::Handle();
   result ^= Api::UnwrapHandle(h_result);
   String& foo = String::Handle(String::New("foo"));
   Integer& expected = Integer::Handle();
   expected ^= foo.HashCode();
   EXPECT(result.IsIdenticalTo(expected));
 }
 
 }  // namespace dart