Turn FastNewContextStub into a HydrogenCodeStub.

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index 0f6c851b0488c239c8d92862c214194ec5a96470..08686e37c9781d1e97c359b25fdd8eda5c353892 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -182,20 +182,22 @@ void FullCodeGenerator::Generate() {
   if (heap_slots > 0) {
     Comment cmnt(masm_, "[ Allocate context");
     // Argument to NewContext is the function, which is still in edi.
-    __ push(edi);
     if (FLAG_harmony_scoping && info->scope()->is_global_scope()) {
+      __ push(edi);
       __ Push(info->scope()->GetScopeInfo());
       __ CallRuntime(Runtime::kNewGlobalContext, 2);
     } else if (heap_slots <= FastNewContextStub::kMaximumSlots) {
       FastNewContextStub stub(heap_slots);
       __ CallStub(&stub);
     } else {
+      __ push(edi);
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
     }
     function_in_register = false;
-    // Context is returned in both eax and esi.  It replaces the context
-    // passed to us.  It's saved in the stack and kept live in esi.
-    __ mov(Operand(ebp, StandardFrameConstants::kContextOffset), esi);
+    // Context is returned in eax.  It replaces the context passed to us.
+    // It's saved in the stack and kept live in esi.
+    __ mov(esi, eax);
+    __ mov(Operand(ebp, StandardFrameConstants::kContextOffset), eax);
 
     // Copy parameters into context if necessary.
     int num_parameters = info->scope()->num_parameters();