Fixes a small bug in a MIPS stub.

runtime/vm/stub_code_mips.cc

 // Copyright (c) 2013, 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 "vm/globals.h"
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 1048 matching lines @@
   __ lw(T3, Address(SP, 2 * kWordSize));
   __ beq(CMPRES, ZR, &L);
   __ delay_slot()->addiu(SP, SP, Immediate(3 * kWordSize));
   __ Ret();
 
   // Handle overflow: Call the runtime leaf function.
   __ Bind(&L);
   // Setup frame, push callee-saved registers.
 
   __ EnterCallRuntimeFrame(0 * kWordSize);
-  __ lw(T0, FieldAddress(CTX, Context::isolate_offset()));
+  __ lw(A0, FieldAddress(CTX, Context::isolate_offset()));
   __ CallRuntime(kStoreBufferBlockProcessRuntimeEntry);
   __ TraceSimMsg("UpdateStoreBufferStub return");
   // Restore callee-saved registers, tear down frame.
   __ LeaveCallRuntimeFrame();
   __ Ret();
 }
 
 
 // Called for inline allocation of objects.
 // Input parameters:
@@ skipping 1082 matching lines @@
   __ mov(TMP1, ZR);
   __ lw(T0, Address(SP, 0 * kWordSize));
   __ lw(T1, Address(SP, 1 * kWordSize));
   __ Ret();
   __ delay_slot()->addiu(SP, SP, Immediate(2 * kWordSize));
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS