Link function contexts directly to the previous context.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 459ef15756a5b11d26cf238e33070a30816c9144..a20ab718e4ff2c5d520850b1c8b28e5360b9b725 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -138,14 +138,11 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
   __ Set(ebx, Immediate(0));  // Set to NULL.
   __ mov(Operand(eax, Context::SlotOffset(Context::CLOSURE_INDEX)), ecx);
   __ mov(Operand(eax, Context::SlotOffset(Context::FCONTEXT_INDEX)), eax);
-  __ mov(Operand(eax, Context::SlotOffset(Context::PREVIOUS_INDEX)), ebx);
+  __ mov(Operand(eax, Context::SlotOffset(Context::PREVIOUS_INDEX)), esi);
   __ mov(Operand(eax, Context::SlotOffset(Context::EXTENSION_INDEX)), ebx);
 
-  // Copy the global object from the surrounding context. We go through the
-  // context in the function (ecx) to match the allocation behavior we have
-  // in the runtime system (see Heap::AllocateFunctionContext).
-  __ mov(ebx, FieldOperand(ecx, JSFunction::kContextOffset));
-  __ mov(ebx, Operand(ebx, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  // Copy the global object from the previous context.
+  __ mov(ebx, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
   __ mov(Operand(eax, Context::SlotOffset(Context::GLOBAL_INDEX)), ebx);
 
   // Initialize the rest of the slots to undefined.