Introduce DisallowDeoptimization scope.

src/assert-scope.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 32 matching lines @@
   HANDLE_DEREFERENCE_ASSERT,
   DEFERRED_HANDLE_DEREFERENCE_ASSERT,
   CODE_DEPENDENCY_CHANGE_ASSERT,
   LAST_PER_THREAD_ASSERT_TYPE
 };
 
 
 enum PerIsolateAssertType {
   JAVASCRIPT_EXECUTION_ASSERT,
   JAVASCRIPT_EXECUTION_THROWS,
-  ALLOCATION_FAILURE_ASSERT
+  ALLOCATION_FAILURE_ASSERT,
+  DEOPTIMIZATION_ASSERT
 };
 
 
 class PerThreadAssertData {
  public:
   PerThreadAssertData() : nesting_level_(0) {
     for (int i = 0; i < LAST_PER_THREAD_ASSERT_TYPE; i++) {
       assert_states_[i] = true;
     }
   }
@@ skipping 197 matching lines @@
     NoThrowOnJavascriptExecution;
 
 // Scope to document where we do not expect an allocation failure.
 typedef PerIsolateAssertScopeDebugOnly<ALLOCATION_FAILURE_ASSERT, false>
     DisallowAllocationFailure;
 
 // Scope to introduce an exception to DisallowAllocationFailure.
 typedef PerIsolateAssertScopeDebugOnly<ALLOCATION_FAILURE_ASSERT, true>
     AllowAllocationFailure;
 
+// Scope to document where we do not expect deoptimization.
+typedef PerIsolateAssertScopeDebugOnly<DEOPTIMIZATION_ASSERT, false>
+    DisallowDeoptimization;
+
+// Scope to introduce an exception to DisallowDeoptimization.
+typedef PerIsolateAssertScopeDebugOnly<DEOPTIMIZATION_ASSERT, true>
+    AllowDeoptimization;
+
 } }  // namespace v8::internal
 
 #endif  // V8_ASSERT_SCOPE_H_