Fix a duplicate AST ID recorded for for/in.

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 18c9319c62006a243d48613cd3149e12e47c5ae2..e807d658b6cde01318e993bea223f164da13a172 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -1984,10 +1984,20 @@ void FullCodeGenerator::EmitAssignment(Expression* expr, int bailout_ast_id) {
     }
     case KEYED_PROPERTY: {
       __ push(eax);  // Preserve value.
-      VisitForStackValue(prop->obj());
-      VisitForAccumulatorValue(prop->key());
-      __ mov(ecx, eax);
-      __ pop(edx);
+      if (prop->is_synthetic()) {
+        ASSERT(prop->obj()->AsVariableProxy() != NULL);
+        ASSERT(prop->key()->AsLiteral() != NULL);
+        { AccumulatorValueContext for_object(this);
+          EmitVariableLoad(prop->obj()->AsVariableProxy()->var());
+        }
+        __ mov(edx, eax);
+        __ Set(ecx, Immediate(prop->key()->AsLiteral()->handle()));
+      } else {
+        VisitForStackValue(prop->obj());
+        VisitForAccumulatorValue(prop->key());
+        __ mov(ecx, eax);
+        __ pop(edx);
+      }
       __ pop(eax);  // Restore value.
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
       EmitCallIC(ic, RelocInfo::CODE_TARGET);