Link function contexts directly to the previous context.

src/ia32/macro-assembler-ia32.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 1741 matching lines @@
   // Load the JavaScript builtin function from the builtins object.
   GetBuiltinFunction(edi, id);
   // Load the code entry point from the function into the target register.
   mov(target, FieldOperand(edi, JSFunction::kCodeEntryOffset));
 }
 
 
 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.
-    mov(dst, Operand(esi, Context::SlotOffset(Context::CLOSURE_INDEX)));
-    // Load the function context (which is the incoming, outer context).
-    mov(dst, FieldOperand(dst, JSFunction::kContextOffset));
+    mov(dst, Operand(esi, Context::SlotOffset(Context::PREVIOUS_INDEX)));
     for (int i = 1; i < context_chain_length; i++) {
-      mov(dst, Operand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
-      mov(dst, FieldOperand(dst, JSFunction::kContextOffset));
+      mov(dst, Operand(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).
     mov(dst, esi);
   }
 
   // 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 361 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32