Fix clobbered register when setting this_function variable.

src/x87/full-codegen-x87.cc

Index: src/x87/full-codegen-x87.cc
diff --git a/src/x87/full-codegen-x87.cc b/src/x87/full-codegen-x87.cc
index 4ee27490a9bf03024839ca3bf9794791eb3e83bb..cd49e0aa08d5cd37833da162e08a23ec36beb175 100644
--- a/src/x87/full-codegen-x87.cc
+++ b/src/x87/full-codegen-x87.cc
@@ -236,6 +236,10 @@ void FullCodeGenerator::Generate() {
   Variable* this_function_var = scope()->this_function_var();
   if (this_function_var != nullptr) {
     Comment cmnt(masm_, "[ This function");
+    if (!function_in_register) {
+      __ mov(edi, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
+      // The write barrier clobbers register again, keep is marked as such.
+    }
     SetVar(this_function_var, edi, ebx, edx);
   }