[turbofan] Avoid unnecessary write barriers and improve code generation.

src/compiler/mips/instruction-codes-mips.h

Index: src/compiler/mips/instruction-codes-mips.h
diff --git a/src/compiler/mips/instruction-codes-mips.h b/src/compiler/mips/instruction-codes-mips.h
index c4c8aa075b8f22248fdeea004a4da6a005db9aaf..a251ba93ca5cf460756eb8f7aba5add86cff2c7a 100644
--- a/src/compiler/mips/instruction-codes-mips.h
+++ b/src/compiler/mips/instruction-codes-mips.h
@@ -85,8 +85,7 @@ namespace compiler {
   V(MipsFloat32Min)                \
   V(MipsPush)                      \
   V(MipsStoreToStackSlot)          \
-  V(MipsStackClaim)                \
-  V(MipsStoreWriteBarrier)
+  V(MipsStackClaim)
 
 
 // Addressing modes represent the "shape" of inputs to an instruction.