Use the previous context link when checking context extension objects.

src/mips/macro-assembler-mips.cc

 // Copyright 2011 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 3553 matching lines @@
     while (abort_instructions++ < kExpectedAbortInstructions) {
       nop();
     }
   }
 }
 
 
 void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
   if (context_chain_length > 0) {
     // Move up the chain of contexts to the context containing the slot.
-    lw(dst, MemOperand(cp, Context::SlotOffset(Context::CLOSURE_INDEX)));
-    // Load the function context (which is the incoming, outer context).
-    lw(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
+    lw(dst, MemOperand(cp, Context::SlotOffset(Context::PREVIOUS_INDEX)));
     for (int i = 1; i < context_chain_length; i++) {
-      lw(dst, MemOperand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
-      lw(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
+      lw(dst, MemOperand(dst, Context::SlotOffset(Context::PREVIOUS_INDEX)));
     }
   } else {
     // Slot is in the current function context.  Move it into the
     // destination register in case we store into it (the write barrier
     // cannot be allowed to destroy the context in esi).
     Move(dst, cp);
   }
 
   // We should not have found a 'with' context by walking the context chain
   // (i.e., the static scope chain and runtime context chain do not agree).
@@ skipping 520 matching lines @@
        opcode == BGTZL);
   opcode = (cond == eq) ? BEQ : BNE;
   instr = (instr & ~kOpcodeMask) | opcode;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS