Skip write barriers in the fast case when setting up local context.

src/objects.h

 // 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include "allocation.h"
 #include "assert-scope.h"
 #include "builtins.h"
@@ skipping 1053 matching lines @@
   V(kExpectedFixedArrayInFeedbackVector,                                      \
     "Expected fixed array in feedback vector")                                \
   V(kExpectedFixedArrayInRegisterA2,                                          \
     "Expected fixed array in register a2")                                    \
   V(kExpectedFixedArrayInRegisterEbx,                                         \
     "Expected fixed array in register ebx")                                   \
   V(kExpectedFixedArrayInRegisterR2,                                          \
     "Expected fixed array in register r2")                                    \
   V(kExpectedFixedArrayInRegisterRbx,                                         \
     "Expected fixed array in register rbx")                                   \
+  V(kExpectedNewSpaceObject, "Expected new space object")                     \
   V(kExpectedSmiOrHeapNumber, "Expected smi or HeapNumber")                   \
   V(kExpectedUndefinedOrCell,                                                 \
     "Expected undefined or cell in register")                                 \
   V(kExpectingAlignmentForCopyBytes,                                          \
     "Expecting alignment for CopyBytes")                                      \
   V(kExportDeclaration, "Export declaration")                                 \
   V(kExternalStringExpectedButNotFound,                                       \
     "External string expected, but not found")                                \
   V(kFailedBailedOutLastTime, "Failed/bailed out last time")                  \
   V(kForInStatementIsNotFastCase, "ForInStatement is not fast case")          \
@@ skipping 9985 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_